Fortunately for you, in the last couple of weeks, I have interviewed our deliverability experts, developers, as well as marketers, and asked them for recommendations. I tested each email infrastructure provider they recommended, and here are the results!

If you want to skip ahead, you can do so by clicking on some of the following links:

• A snapshot of the platforms
• Detailed reviews of each platform
• In-depth comparison criteria

Best email infrastructure platforms for developers: a snapshot

Click on a platform name to jump ahead to the detailed review.

• Mailtrap is the best email infrastructure for developer and product teams who need high inboxing rates, fast email delivery, and 24/7 expert support.
• SendGrid is for teams that need a scalable email delivery service with a lot of quality-of-life features.
• Mailgun offers developer teams an email infrastructure with detailed email logs, a validation API, and extra features to tweak their sending configuration.
• Amazon SES is for experienced developers who are already deep in the AWS ecosystem and want to go easy on their budget.
• Postmark offers a minimalistic yet configurable email infrastructure for teams that need to send transactional emails with no extra features.

For your convenience, here’s a quick comparison of the email infrastructure platforms:

Disclaimer: The ratings, features, and prices are up-to-date at the time of writing this article, but they may be different when you’re reading it, as they’re prone to change.

What is an email infrastructure platform?

An email infrastructure platform is a platform that provides you with the tools you need to send and control emails reliably. That is, without having to build and maintain that infrastructure yourself.

Such a platform should allow you to send both transactional (e.g., password resets) and marketing emails, like newsletters and product updates. So, best case scenario: an email infrastructure platform should cater to both developers and marketers, but that’s not always the case.

However, you typically need all bases covered if you are:

• Sending a high-volume of emails
• A startup or a fast-growing product
• In a regulated industry, and you need a reliable email infrastructure

In case you’re a solopreneur with a vibe coding project, you can do well with just an email API or SMTP service.

On the other hand, if you need to send notifications in other channels, you can also use notification infrastructure services like Knock, which integrate with providers like Mailtrap to help you orchestrate your messages across email, SMS, push, chat, and even supports in-app messaging.

What to consider when choosing an email infrastructure solution?

Over at Mailtrap, we leave nothing to chance and leave no stone unturned. That’s why, before creating this list, I conducted thorough research and tested each email infrastructure solution I present here.

Documentation research

Before creating an account for each email infrastructure platform, I dug through:

• Official API documentation to see how flexible and configurable an email infrastructure is, how many use cases it covers, what it offers, etc.
• User reviews and testimonials to have a better idea of what the community thinks about platforms and whether they stay true to their advertised promises.
• Blogs and help centers to check if there are any helpful step-by-step tutorials that can help you set up an infrastructure and start sending emails.

Hands-on testing

Once I was done with the extensive documentation research, I verified my sending domains and:

• Sent transactional emails since they’re the heart of every email campaign and pretty much mandatory for most businesses nowadays.
• Launched email campaigns to see how well I could promote my product and keep in touch with my users. I’ve also played around with contact management.
• Tried out email template design tools and personalized my messages as much as I could, testing templating logic and dynamic content along the way.

In the following section, we’ll start with the reviews of each email infrastructure platform. However, if you’re interested in checking out the criteria I used in detail, click here.

Best email infrastructure provider: Mailtrap

G2: 4.8 🌟 Capterra: 4.8 🌟

Mailtrap is an email platform for developer and product teams that offers high inboxing rates, fast email delivery, and 24/7 expert support. It’s best for digital product companies that need to send transactional and bulk emails at scale.

To achieve high inboxing rates, Mailtrap uses separate sending streams for transactional and bulk emails, dedicated IPs, email warm-up, throttling, and other features. 

Most importantly, you’ll see high rates regardless of the plan, since they’re there by design.

Recently, Mailtrap has gone a step further and conducted deliverability tests with the top email infrastructure platforms. We’ve used free plans, didn’t warm up domains, sent the same email template, and covered a few other technical tidbits to make the tests 100% fair. Here’s how Mailtrap performed: 

However, sending emails without knowing where they are landing would be like shooting in the dark, wouldn’t it? That’s why Mailtrap has helicopter view dashboards and drill-down reports, with which you can track important email metrics like opens, clicks, bounces, etc.

See a discrepancy in your email metrics or simply want to improve their performance? You can do so with the help of Mailtrap’s expert consultants, who can help you with any potential issues or simply give you a hand with email deliverability optimization. Of course, there’s also Mailtrap’s customer support team that works around the clock, which you can reach via tickets or live chat.

Key features:

• Strong deliverability features
• Fast email delivery
• Industry-best analytics
• Safe and fast scaling
• 24/7 expert support
• GDPR compliant
• ISO/IEC 27001:2022 certified
• Advanced webhooks
• Email marketing suite
• Comprehensive API documentation
• Integration to MCP servers via Claude, Cursor, or VSC code editor.

Pricing

To help you scale efficiently (and affordably), Mailtrap offers several straightforward pricing plans, along with a slider that lets you choose your monthly email sending volume. Here’s a quick summary table:

For more details, please consult the official Mailtrap pricing page.

Developer experience

Official API documentation

Mailtrap offers easy-to-use SDKs for Node.js, PHP, Ruby, Python, Elixir, and Java.

If you’re a developer, you’ll appreciate Mailtrap for its straightforward approach to email sending. Namely, to start using the platform, all you need to do is verify your domain and copy/paste the pre-made code snippet of the programming language or framework you’re using.

For instance, if you want to send emails with Flask, a popular Python framework, you could just use this pre-made snippet and insert your credentials, simple as that:

app.config['MAIL_SERVER']='live.smtp.mailtrap.io'
app.config['MAIL_PORT'] = 587
app.config['MAIL_USERNAME'] = 'api'
app.config['MAIL_PASSWORD'] = '<YOUR_API_TOKEN>'
app.config['MAIL_USE_TLS'] = True
app.config['MAIL_USE_SSL'] = False

Moreover, if you ever get stuck or lost in the process, Mailtrap has a comprehensive knowledge base with a plethora of step-by-step articles, as well as a blog, and, wait for it, even a YouTube channel. For example, if you want to add sending functionality for Python applications, here’s a dedicated tutorial you could follow.

Security & compliance

Mailtrap checks a lot of boxes when it comes to email security & compliance, from super solid email authentication to GDPR compliance. Additionally, it is ISO certified, while SOC 2 certification is on the way. 

Testimonials

When it comes to user testimonials, I am happy to see that Mailtrap gets a lot of love on the web. It’s praised for deliverability, separate sending streams, and working well at scale.

Another user, a developer, says Mailtrap’s analytics help him notice delivery issues quickly and that the platform delivers as expected. 

SendGrid

G2: 4.0 🌟 Capterra: 4.2 🌟 Trustpilot: 1.1 🌟

SendGrid by Twilio is a communication platform for transactional and marketing email sending. It offers an email API and SMTP relay for developers, whereas marketers can use its campaign builder to launch campaigns.

It’s a solid choice for teams that need a scalable email delivery service with a lot of quality-of-life features.

By quality-of-life features, I mean automatic IP warm-up and throttling, ready-made code snippets, engagement quality API, and a few others. Although these aren’t mandatory by any means, they can be quite useful for email infrastructure optimization.

Moving on, another notable SendGrid feature is its deliverability insights dashboard, where you can track the most important deliverability metrics, such as delivered, bounced, opens, etc. You can also see what’s causing your emails to bounce, track deliverability trends, filter metrics by top mailbox providers, and more.

Speaking of mailbox providers, I must note that SendGrid had mixed deliverability test results when it comes to providers like Yahoo, Outlook, and AOL.

Key features:

• Solid analytics
• High sending throughput
• Granular user control
• Email validation API
• Onboarding assistance
• SMS support via Twilio
• CRM support
• Pre-warmed up, geo-specific IPs

Pricing

When it comes to pricing, SendGrid doesn’t beat around the bush. Namely, it has two pricing tiers with a custom one for enterprise users, along with a slider for selecting your desired email volume. 

Although I don’t like the fact that the free plan only lasts for 30 days and that costs do ramp up if you want to send more than 100,000 emails/month or use dedicated IPs. Moreover, if you want to send email marketing campaigns, you need to pay for a separate pricing plan.

For more details, please consult the official SendGrid pricing page.

Developer experience

Official API documentation

SendGrid supports C#, Go, Java, Node.js, PHP, Python, and Ruby.

The platform has made sure that the onboarding process is as smooth as possible, providing everything from guides on setting up your email infrastructure to an extensive API documentation. Similarly to Mailtrap, SendGrid also offers pre-made snippets for easier sending.

Lastly, in case you get stuck or if you’re facing an issue, you can contact SendGrid’s customer support via ticket, chat, or phone. However, its availability is a bit limited to different pricing tiers, and I’ve seen some concerning remarks about it.

Security & compliance

One of the security features that stood out to me with SendGrid is its IP Access Management, which lets you control who can access your account based on their IP address. As for compliance, it passes pretty much all checks.

Testimonials

While scouring the web for online user testimonials for SendGrid, I’ve noticed that people are generally satisfied with how easy it is to integrate and its validation functionality. However, some users think you need experience setting up DNS records to complete the email infrastructure configuration.

Other users think SendGrid’s email API is one of the most reliable out there and claim that the platform reduced their bounce rates, although they’re not satisfied with the pricing.

Mailgun

G2: 4.2 🌟 Capterra: 4.3 🌟Trustpilot: 4.1 🌟

Mailgun is a transactional email service that provides an SMTP and email API, with an infrastructure that’s, according to its creators, ‘designed for developers, by developers.’ 

Due to its technical nature, it’s specifically suited for developer teams who need detailed email logs, a validation API, and extra features to tweak their infrastructure.

More specifically, Mailgun keeps your email logs for up to 30 days, and you can filter them by event types, list name, tag names, and some other categories. This specificity works like a charm for tracking down exactly where your emails went, where they landed, and everything that happened in between.

Additionally, Mailgun has an email validation API, which you can use to perform everything from basic syntax checks to cross-reference your email list against Mailgun’s huge database of addresses (450 billion, to be more specific).

When it comes to sending emails, Mailgun offers Rapid Fire Delivery SLA for its end-tier users and high-volume senders. It promises reliable sending of up to 15,000,000 emails per hour and swift delivery.

As for deliverability, Mailgun is as solid as they come, although it sent a significant portion of emails to spam in our tests. So, you be the judge.

Key features:

• EU and US data centers
• Scalable infrastructure
• Email validation
• Onboarding support
• Inbound email support
• Solid compliance
• Robust documentation
• Developer-friendly email infrastructure tools

Pricing

Mailgun has a solid free plan that lets you send 100 emails per day, with the paid plans starting from $15. One of the few downsides that I must mention is that the logs are kept for quite a short time if you don’t use its most expensive plan, and that dedicated IPs cost $59 per month.

For more details, please consult the official Mailgun pricing page.

Developer experience

Official API documentation

Mailgun supports Python, Go, Node.js, PHP, Java, and Ruby.

Regardless of whether you want to send or validate emails, the documentation is geared towards developers more so than the average Joe, with scripts, error logs, and whatnot.

The platform also offers pre-made code snippets for various programming languages, although they are not as detailed as the scripts other platforms offer. Nonetheless, they still get the job done. 

Security & compliance

After researching its compliance and security documentation, I think it’s safe to say that Mailgun is quite a secure email infrastructure platform. 

Testimonials

Mailgun is one of the few email infrastructure platforms that actually has mostly positive reviews on Trustpilot, which is a ratings website notorious for negative comments. Most users there praise Mailgun for its reliable customer support, like Jessica in the screenshot below:

The situation was similar on other review websites, with users praising the platform’s straightforward integration and email sending reliability. However, I’ve noticed some users also agree with me on the lack of example code.

Amazon SES

G2: 4.3 🌟Capterra: 4.7 🌟Trustpilot: 2.3 🌟

Amazon SES (Simple Email Service) is a cloud-based email service provider that’s anything but simple. Nonetheless, it’s a reliable solution for experienced developers who are already deep in the AWS ecosystem, since it uses the AWS Global Infrastructure.

If you or your dev team are tech-savvy, you can configure Amazon SES in a lot of ways to fit your sending needs. You can configure your IPs, encryption, event archiving, and a plethora of other things.

Besides offering a highly configurable email infrastructure, another benefit of Amazon SES is that it can be integrated with many AWS services. These include Lambda for executing backend logic on email events, CloudWatch for monitoring metrics, SNS for sending notifications, S3 for storing email content, and the list goes on.

One more thing you can fine-tune with Amazon SES is permissions, which can be adjusted based on users, roles, or systems. This means you can manage your API key authentication and management, separate access for different clients and environments, etc.

And if you’re interested in how Amazon SES performs in terms of deliverability, here are the numbers it reached in our tests:

Moving on from configuration and fine-tuning, it’s also important to note that new Amazon SES accounts start with a high default sending quota. That is, 50,000+ messages per day, to be more precise. Of course, this number can be scaled at your request if it’s not enough for your sending needs.

Key features:

• Highly configurable infrastructure
• Integration with the AWS ecosystem
• Secure and compliant
• Strong and reputable IPs
• Solid webhooks
• A/B testing
• Supports data residency for EU, US, and Asia
• Super affordable and budget-friendly

Pricing

As you might have noticed, I didn’t include a table for the Amazon SES pricing section since the platform doesn’t have tiers or anything of the sort.

Instead, Amazon SES offers a pay-as-you-go pricing model, with the following prices:

• 1,000 emails = $0.10
• 10,000 emails = $1
• 100,000 emails = $10

As for the free plan, you get 3,000 emails per month during the first year after you start using SES. And if you’re using Amazon EC2 and AWS Elastic Beanstalk, you get the first 62,000 emails for free.

For more details, please consult the official Amazon SES pricing page.

Developer experience

Official API documentation

Amazon SES has official libraries for Java, .NET, PHP, Python, Ruby, and Go.

As I have already mentioned, Amazon SES is a great choice for experienced developers who are already in the AWS ecosystem. This is mainly because the UI doesn’t hold your hand, although the documentation really is extensive and has everything you need.

For instance, just check out the main account dashboard. It doesn’t look like your typical email delivery platform, does it?

Similar to Mailgun, I must say that Amazon SES lacks some pre-made code snippets for SMTP integrations, although there are many scripts for setting up its SDKs.

Lastly, setting it up also requires you to take a few extra steps than you usually would. You need to move out of the SES sandbox, create IAM credentials, configure permissions, all on top of verifying your sending domain. So, you be the judge whether this is worth the extra bucks you save thanks to its affordable pricing model.

Security & compliance

Since it’s a part of the Amazon infrastructure, you could already have guessed that Amazon SES has nailed down its security and compliance.

Testimonials

Whether you browse through social media pages or review websites, you’ll see that Amazon SES is often praised for its prices. But, you can also find as many comments on how its services are not friendly to use.

Additionally, I have noticed that people aren’t at all satisfied with the Amazon SES customer support team, which is a shared trait of all things AWS.

Postmark

G2: 4.6 🌟Capterra: 4.9 🌟Trustpilot: 2.1 🌟

Postmark is an email platform catered towards developers who want to send transactional emails. It’s best for teams who are looking for a minimalistic solution, configurable infrastructure, and no extra features.

Namely, Postmark’s API is highly configurable, giving you room to either simplify sending transactional emails or play with your email infrastructure. It supports batching of up to 500 messages per batch, uses Mustachio templates, and you can also connect webhooks for key events like deliveries and opens.

Besides sending emails, you can also use Postmark’s email API to configure inbound servers, parse incoming email, handle inbound email, and more.

Another one of Postmark’s standout features is its separate sending streams. They function like the one provided by Mailtrap, except they can also be configured for custom email types. For example, you can send verification emails through one stream and invoices via another. All of this goes towards improving your chances of landing in the main inboxes.

Another feature that makes Postmark stand out from the rest of the competition are email logs, which are not only detailed, but are also kept for up to 45 days. And no, it doesn’t depend on your pricing plan, you actually get detailed email logs for this long on all plans. However, you can pay to keep logs for up to 365 days, which can be handy if you plan on conducting audits.

Key features:

• Minimalistic interface
• Fast email delivery
• Separate sending streams
• Inbound processing
• Developer-friendly
• Email logs for up to 45 days
• Transparent deliverability status
• Extensive documentation
• Offers MCP agents

Pricing

Although many people say that Postmark’s pricing has gone up since it was acquired by ActiveCampaign, I’d say that it still has an affordable and generous model. For instance, you get 5 domains, 15 streams, and 45 days of email logs even on the basic plan.

However, it has a few add-ons, such as dedicated IPs, which cost $50/month and for which you need to be sending 300,000 emails per month or more. You can also pay for custom activity retention and DMARC monitoring, which are not needed but are appreciated. 

For more details, please consult the official Postmark pricing page.

Developer experience

Jump to: Official API documentation

Postmark has official libraries for Ruby, RoR, .NET, Java, PHP, and Node.js.

As you’ll notice after spending only a few minutes in the Postmark dashboard, you’ll notice that this email infrastructure platform is super intuitive to use, especially if you’re a developer. You’ve got everything you need to start sending emails laid out for you, and the setup is super simple.

API documentation is clear and has code snippets you can use to configure the service, either via its email API and SMTP service.

Security & compliance

Postmark is a secure email infrastructure platform, although I should note that it has servers in the US and doesn’t have HIPAA certification.

Testimonials

Besides Postmark’s customers page, I checked out what review websites have to say about the platform. Most users praise the platform for its deliverability and straightforward interface, although there are some who don’t like its pricing model.

Postmark’s email API also gets a lot of praise, as well as its ability to send transactional emails. However, I’ve noticed a few negative comments about its customer support, which makes sense since it can only be reached via tickets.

Email infrastructure services comparison criteria

In the following section, I’ll describe the criteria I used to find the best email infrastructure services on the market.

Email deliverability & performance

To help their users reach the best deliverability rates, providers typically use a combination of dedicated IPs, proper warmup protocols, and more. Additionally, for optimal performance, most infrastructures nowadays are cloud-based.

Also, speaking of deliverability, I must note that there’s a noticeable discrepancy in rates between different providers. To paint you a better picture, here are the results from the recent deliverability tests we conducted over at Mailtrap:

Note: To make sure the tests were fair to everyone, we used free plans, shared IPs, and identical email templates for all providers. For more information on our testing methodology, be sure to check out our deliverability comparison guide.

Scalability & throughput handling

Scalability refers to how well an email infrastructure provider is able to allow you to increase your business’s sending volume without facing any bottlenecks or deliverability issues.

For example, if you want to increase your sending throughput from 50k emails/month to 150k, you should be able to do it without any increases in bounces, spam rates, etc.

So, a provider should give you some control over their infrastructure, in terms of queuing, and especially throttling, which lets you limit how many emails you can send per second or minute. All of this goes a long way in avoiding spam filters and sending emails with peace of mind.

Reliability & uptime guarantees

Although every email infrastructure promises reliability, to ensure there are no loose bolts, I’ve checked documentation for data on datacenter distribution, backup mechanisms, load balancing, and database replication.

Moreover, I’ve visited status pages with real-time uptime metrics, like this one, for example, and service-level agreements (SLAs), if there were any. This way, I was able to get a better idea of whether a provider is actually reliable or not.

Deliverability analytics & monitoring

Although not all, most transactional emails need to land in your recipients’ inboxes in order to move them down the funnel. For example, a new user registers at your website and needs to verify their email before continuing to shop. If the verification email misses their inbox, they might give up trying to register and ditch the shopping.

Not to mention all of the latest email marketing laws and regulations imposed by the most popular inbox providers.

That’s why it’s super important to monitor your key email deliverability performance metrics. These include delivered rate, bounce rate, spam complaints, and body. And every serious email infrastructure provider will provide you with advanced analytics, including a dashboard or two, where you can track your metrics.

Dedicated IP & IP pools

A feature that goes a long way, especially if you’re a high-volume sender, is having dedicated IPs. Compared to shared IPs, dedicated ones are used solely by one sender and give you complete control over your sending.

Most email infrastructure platforms include them in mid-to-end tier plans, although some also offer them as separate add-ons, which I’ll be sure to mention in the article.

Some providers also offer separate sending streams, which allow you to send transactional messages at the same time as marketing emails without your deliverability and sender reputation taking a hit. However, there’s a big difference between a separate sending infrastructure that consists of IP pooling and dedicated IPs, and a true separate stream. 

Here’s an overview of what each email infrastructure provider on this list offers in terms of separate sending streams:

Pricing comparison

Pricing-wise, I have made sure not to include any platforms on this list that have hidden costs and auto-charges. What I mean by this is that many email providers charge you automatically when you go over their contact or sending limits.

Additionally, I have checked whether important features like dedicated IPs and email templates are available to all plans or they’re reserved to premium tiers or as add-ons.

And if you’re interested in the sending costs for each platform on this list, here’s a quick summary:

Transactional email sending

Every email infrastructure platform needs to provide the tools for reliable sending of user-triggered, or transactional, emails. This is especially true if you’re a high-volume email sender.

SMTP & email API

One of the first must-haves for any developer-friendly email infrastructure is an SMTP service with pre-written code snippets for popular programming languages and frameworks. You can simply copy/paste these into your configuration and start sending emails right away.

The provider should also offer a regularly maintained and updated email API that supports major SDKs like Go, Ruby, Python, Node.js, PHP, etc. These allow you to integrate the infrastructure into your app without spending too much time on it.

Webhooks

Webhooks are the bread and butter for any dev who is serious about their sending configuration. They let you track events in real time, get delivery status notifications, handle spam and bounced messages, and more.

However, not every email infrastructure provider offers the same range of webhook events or has fast error handling.

MCP server

As you might already know, MCP servers are the new kids on the AI block, helping developers send code-free emails using their favorite robot helpers or editors.

Now, I’m not saying every email infrastructure platform must offer MCPs, but let’s face it: they are a nice quality-of-life feature that can make your life easier.

For example, platforms like Mailtrap and Postmark offer MCP servers, which you can hook up to your IDE. Then, you can test your emails locally and then send them when you’re ready, which is a nice way to smooth out your production process.

Transactional emails performance analytics

Previously in the article, I mentioned deliverability analytics and monitoring of the most important email marketing metrics. But what if you want to know details like the status of your sent emails, when it was delivered, to which inbox they went, etc?

For this, email infrastructure platforms usually have email logs, which typically range from 15 to 60 days of retention, depending on the plan you choose. So, I’ll make sure to point out how long you get to keep your emails with each provider on the list, and a few other important details.

And, here’s another table that summarizes email log retention for each of the providers:

Marketing email sending

If you want to send marketing emails on top of transactional messages, an email infrastructure provider should ensure high deliverability for targeted marketing campaigns, as well as provide you the tools you need to send targeted campaigns.

Campaign management

Although you can technically send email marketing campaigns via an email API, let’s be honest: it’s not the most optimal way to go about it. That’s why most platforms offer a UI with a campaign wizard that guides you through content creation, list uploading, scheduling, etc.

Contacts management 

Contact management via an API is a whole different story since you want a convenient way to collect your sign-ups and turn them into contacts in your email list. Some providers offer contact APIs, like this one, for instance.

With these, you can set up automatic collection of new sign-ups, without having to enter them manually.

Workflow automation & triggers

Whether you’re sending strictly transactional or marketing emails, you need automations to provide a smooth customer experience, move your users down your funnel, or even clean up your list. 

For instance, you can set up an automated follow-up for new sign-ups or send an email whenever someone leaves their cart full without making a purchase.

Some platforms have dedicated workflow builders for this, while others use API triggers to do this. So, a different cup of tea for everyone. 🍵

Campaign optimization

To optimize your email campaigns and see what works best and resonates with your audience, you need to perform A/B testing. This includes testing your subject lines, headings, buttons, etc. 

Email editor & email templates

Nowadays, email infrastructure platforms typically offer some of the following tools to help you create email content:

• Email template features – Templates save you a lot of time, either by giving you a preset for your design or a full-fledged design you can customize according to your liking. However, it’s pretty much the golden standard nowadays to have dynamic templates, which can be personalized for your recipients.
• Drag-and-drop editors – Feeling creative? Use email builders with top design tools to make your ideas come to life by simply dragging and dropping them on the empty canvas. 
• HTML editors – If you’re old school and want to create HTML templates manually, pretty much every platform out there offers an HTML editor. Basically, code on the left – design on the right. Some platforms also let you host your templates and then reference them later via API in production.

Marketing emails performance analytics

Tracking the performance of your marketing emails is equally important as it is for transactional emails. You simply need to be able to see how many of your emails have been delivered, how many have received spam complaints, and how your audience is reacting to them in general.

For this, you can set up custom webhook events or track them via email APIs, but the industry-standard is a dashboard with all of the most important stats presented via graphs or charts. Here’s how we do it over at Mailtrap, for instance:

Security & compliance

Domain authentication & sender reputation

Most inbox providers, like Gmail and Yahoo, require proper domain authentication (SPF, DKIM, and DMARC) for bulk senders. If you don’t have it set up, they have the right to send your emails to the spam folder or even block them altogether.

So, ideally, you’re looking for an email infrastructure platform that ticks all authentication boxes and ensures your sender reputation stays intact.

Data encryption & transmission security

TLS / STARTTLS encryption, event logging, and token-based authentication — these are only some of the security standards providers use to keep your data safe. And here’s a summary of what the platforms in this article use:

P.S. Click here to find out how different providers handle their security.

Compliance certification

A compliance-ready infrastructure is what most providers need to offer nowadays. This means having certification for SOC 2 and supporting GDPR, amongst other things. 

Now, it’s time for another table, this one summarizing the compliance of each email infrastructure provider: 

P.P.S. Interested in learning more about compliance amongst providers? If so, check out our dedicated article.

Onboarding, UX & support

Support

Sometimes, things don’t always go according to plan, especially if you’re dealing with a lot of sending-functionality code, integrating an API, and similar. That’s why every email infrastructure platform should have dedicated support for agencies in case they get stuck.

Some platforms offer chat support and SLA-backed support, while you can reach others via phone or a ticketing system. Therefore, here’s what you can expect regarding customer support from each platform on this list:

Note: The support type and availability mostly depend on the pricing plan you choose. For example, Mailtrap has 24/7 customer support via tickets available to all users, even on the free plan, whereas you need to be a paying user to get support from Mailgun.

Documentation & developer guides

If you want to make your developer team’s lives easier, choose an email infrastructure platform that provides robust documentation with guides they can use for adding sending functionality.

For instance, Mailtrap has prepared for its developers an extensive knowledge base and API documentation where they can find anything they’re looking for: from domain authentication to adding webhooks. Additionally, there’s the Mailtrap blog and even a YouTube channel with dev guides.

Also, many platforms, not only Mailtrap, provide developers with ready-made integrations. These are snippets you can simply copy/paste into your app/project code and start sending in a minute. This goes a long way toward improving user experience, right?

For your convenience, here are the links to each provider’s developer guides. Feel free to compare them and find the one that suits you and your team best:

Support & developer community

For this section of the article, I asked myself the following questions:

• Does the platform provide any official SDKs for easy integration?
• Are there any libraries maintained by the community?
• Has the platform been covered on Stack Overflow or any community forums?
• Does the platform have well-maintained GitHub repositories?

Any email infrastructure platform that didn’t pass these questions didn’t make it to this list. 

And if you’re interested in automating your email sending process by connecting it to a platform’s email API, here are the supported SDKs by each platform:

Customer feedback & reputation

Researching how each of these email infrastructure providers has been received on social media and ratings platforms has probably been the most fun part of writing this article. I’ve seen everything, from community backlashes on X to well-deserved praise on Capterra.

I’ve also read some case studies where I could get a glimpse of how a certain platform helped a specific business reach its goals.

All of this allowed me to see what the general opinion of each of the provider’s user base is and to bring you a non-biased review. With that said, here are the ratings from the most popular review platforms, with their overall rating combined:

Wrapping up

Hopefully, I’ve made it a bit easier for you to choose the best email infrastructure platform for your business/team.

Just remember: not every solution will work the same for everyone. Choose wisely and based on your team’s requirements and needs. Focus on finding good deliverability, scalability, developer-friendly APIs, and the key tools you need to send both transactional and marketing emails.

To sum it up, here are the top providers by use case:

• Mailtrap for sending high-volume emails
• SendGrid for scalable delivery
• Mailgun for experienced developer teams
• Amazon SES for teams using AWS
• Postmark for minimalistic transactional email sending

FAQ

What is email infrastructure?

Email infrastructure is a combination of software and hardware components, such as mail servers, mail transfer agents (MTAs), and IP addresses, that work together behind the scenes to send emails when you press the send button.

What is an email infrastructure provider?

An email infrastructure provider is a service that offers the set of tools you need to send and manage your emails. This way, you can send transactional and marketing messages without having to build an email infrastructure yourself.

What is the best email infrastructure provider?

Although every business has different requirements for its email infrastructure, there is no best email infrastructure provider. However, Mailtrap is an email platform that provides a flexible email infrastructure that can fit most teams, especially those who are looking for high inboxing rates, fast email delivery, and 24/7 expert support.

Luckily, you’ve come to the right place! I’ve interviewed our very own deliverability experts whose opinions are based on the latest state of the industry and years of experience, took their recommendations, tested every platform I mention in this article, and these are the results!

Feel like skipping ahead? Be my guest and click on some of the following jump links:

• A snapshot of the alternatives
• In-depth comparison criteria
• Detailed reviews of each alternative

Disclaimer: The references to software ratings, available features, and pricing were valid at the time of writing this article, but could be subject to change in the future.

Best Postmark alternatives: a snapshot

Click on a platform name to jump ahead to the detailed review.

• Mailtrap is the best Postmark alternative for product companies with large sending volumes looking for high deliverability and industry-best analytics.
• Mailchimp is most suitable for small businesses on a budget who need both email marketing and transactional messaging features.
• Mailgun is a solid choice for experienced developer teams since it’s, as its creators say: ‘made by developers, for developers.’
• SendGrid offers an email marketing suite and SMTP/API services with rich documentation, but has customer support locked for high-tier plans.
• Amazon SES is a great Postmark alternative for experienced developers who are already in the AWS ecosystem.
• Brevo is for businesses that want to send transactional emails and do multi-channel marketing.

Here’s a back-to-back free plan and pricing comparison of each Postmark alternative:

Postmark alternatives comparison criteria

Before we get into actual Postmark alternatives, let me share the criteria I’ve used to come up with the list.

I’ll describe the aspects I’ve benchmarked, provide the comparison tables I came up with, and more. This way, you get a 100% unbiased review with no sponsored links or content, just results from many hours of testing.

Email infrastructure

A solid email infrastructure is the backbone of every email service provider out there, and it consists of deliverability, reliability, and scalability.

Deliverability

Every email that doesn’t reach your recipient’s inbox costs you $0.11, so deliverability, or the platform’s actual ability to have your emails land in the main inboxes instead of going to spam or promotion folders, is crucial.

For example, to have your emails hit the mark, Postmark has strict sending policies in place, uses worldwide data centers, provides separate streams, dedicated IPs as add-ons, and a few other bits and bobs. 

So, I’ll compare what other providers offer in this regard and what they do to help you reach your recipients’ main inboxes.

I’ll also provide you with deliverability rates some of the providers on this list achieved on our recent deliverability tests we performed using free plans, same templates, and shared IPs. Here are the results:

If you feel like exploring this further, feel free to check out the article we’ve prepared for you on the topic of email deliverability comparison. ⬅️

Reliability

When we’re talking about reliability, we’re talking about whether an email service provider is able to consistently deliver your emails without any major hiccups. Additionally, an ESP shouldn’t face delays or downtimes and should offer transparent monitoring of these issues.

For instance, SendGrid advertises a 99.99% uptime, and I was able to see whether this is actually true by visiting its status page. 

Scalability

Scalability is the ESP’s ability to grow with your business, that is, to allow your business to grow without facing bottlenecks, degraded campaign performance, or other major issues.

To be scalable, an ESP should offer some of the following:

• High sending throughput
• Cloud-based infrastructure
• Dedicated IPs or streams
• 24/7 customer support
• Email deliverability consultations

Separate sending stream

As you already know, Postmark offers dedicated sending streams, which you can use to send user-triggered and bulk emails separately.

Now, true separate sending streams are quite rare nowadays, so, on this list, you’ll only see a couple of ESPs that offer them, while the others provide you the tools to separate your streams.

Here’s a quick breakdown of each:

Pricing comparison

To help you decide whether an ESP from this list is more affordable to you compared to Postmark or not, I will break down:

• Different pricing plans and features they bring to the table
• Price per sent email compared to Postmark
• Key pricing differences between each provider and Postmark

And here’s a table for you to get a brief idea of the Postmark alternatives pricing:

Transactional email sending

To help you send transactional emails easily, that is, welcome emails, password resets, etc., Postmark offers an SMTP server with pre-made snippets and a flexible email API. 

So, in this article, I’ll list ESPs that offer similarly rich documentation and APIs that support integration with major programming languages. In case you’re an API heavy user and need a plethora of integration options, here’s a breakdown of supported libraries for each provider:

Marketing email sending

Marketing email sending is quite a different story from transactional, since you’re sending campaigns instead of user-triggered messages. Currently, Postmark doesn’t offer this functionality.

In case you’re transitioning because of that, I’ll list some ESPs that can help you optimize your email marketing funnel, namely:

• Manage your contacts
• Track performance metrics
• Perform A/B testing
• Automate workflows

Essentially, these are just the features you can use to grow your business via email marketing.

AI, automations, integration

AI in email marketing

AI in email marketing has stopped being a gimmick a while ago. For example, Postmark offers MCP servers, with which you can prompt your AI assistants to send emails, use templates, track performance metrics, or even manage whole campaigns in your stead.

Moreover, ESPs have started integrating AI for audience segmentation, generating subject lines or even email content itself. 

So, I’ll make sure to point out useful AI tools I tried and tested throughout the reviews.

Integration

Although Postmark doesn’t offer many integrations, it has several useful ones, like the one with ActiveCampaign, its parent company. You can use it to get some basic email marketing functionality, then pair Postmark with Mailcoach or Craft Campaign to take your campaigns further.

However, if you’re looking for advanced integrations, I’ll be mentioning ESPs on this list that offer them.

Email design

Coding email designs has long been a thing of the past. Most ESPs nowadays offer some of the following features to make your email creation process as seamless as possible:

• Drag-and-drop editor – A solid drag-and-drop email builder lets you arrange your email according to your preferences, tweak the layout, preview mobile and desktop versions, and more. Everything without having to go anywhere near your HTML code editor.
• Email templates – If an ESP doesn’t offer its own native templates, it at least provides an integration for them. For this article, I checked not only how many template options you get for each ESP but also how good-looking they are.

User experience

An ESP should make your life easier, not harder, especially if you’re transitioning from another solution. That’s why, when writing these reviews, I always ask myself the following questions:

• Is the platform user-friendly? Is it oriented towards marketers or devs?
• How can I reach the platform’s customer support, and when are they available?
• Do I get any migration help if I’m coming from another service?
• Can I consult with the platform’s deliverability experts?

To sum it up and answer these questions, here’s a nice little table for you:

Customer experience

Postmark is quite transparent in terms of its customer success stories on its homepage, so I’ve checked what users have to say for each ESP on this list.

I’ve scoured online customer testimonials and reviews on websites like G2 and Capterra, and even checked social media. There, I was able to learn a great deal about the platforms, including whether they have been facing downtimes, unresponsive customer support, and more.

Most importantly, I tried to find reviews from people who have transitioned from Postmark to see what made them migrate and whether they’re satisfied with the transition.

Security

To see how each ESP on this list handles security aspects like DMARC protection, API key security, event logging, authentication, etc., I checked pages like this one, for example. 

Here’s a quick summary for you:

Compliance

If you want to remain compliant with all the email marketing laws like GDPR or the CAN-SPAM Act, you need to switch to a provider that will make it easy to do so.

Quick breakdown:

Best Postmark alternative: Mailtrap Email Delivery Platform

G2: 4.8 🌟 Capterra: 4.8 🌟

Mailtrap Email Delivery Platform is designed for product companies with high sending volumes. It’s best for businesses that need high deliverability rates, growth-focused features, and industry-best analytics.

Notable features:

• High deliverability rates

Mailtrap places a strong focus on helping its users achieve high deliverability rates and land in their recipients’ main inboxes. It achieves this by offering dedicated IP addresses, domain or IP warmup, throttling, and, similar to Postmark, dedicated sending streams.

Here’s how Mailtrap performed compared to Postmark in our recent deliverability tests:

• Growth-focused features

Mailtrap offers a fast-scaling infrastructure that allows fast-growing businesses to increase their sending volume without experiencing any delays, issues, or drops in deliverability rates.

You can even contact the platform’s deliverability experts to fine-tune your sending configuration, set up webhooks to listen to various events, and more. Additionally, I have to mention that Mailtrap’s customer support is available 24/7 for all plans, so you can count on their help in case you face an unexpected blocker.

• Industry-best analytics 

With Mailtrap, you can observe the performance of your emails through helicopter-view dashboards and drill-down reports. There, you’ll be able to see your opens, deliveries, unsubscribes, bounces, and more.

Additionally, you can see how your emails are doing with each provider.

How is Mailtrap different from Postmark?

The biggest difference between the two platforms is that Mailtrap offers a suite of email marketing tools. You can use these to upload your contacts, create an email template, schedule a campaign, and then track its performance after it’s launched.

And, although Mailtrap offers separate streams like Postmark, you cannot make custom ones for different types of email. Instead, you get a separate stream for transactional emails and one for bulk emails, which allows you to send user-triggered and promotional emails at the same time without sacrificing your deliverability.

Pros

• High deliverability rates
• Separate sending stream
• Industry-best analytics
• GDPR compliant
• ISO/IEC 27001:2022 certified 
• Extensive documentation for your devs
• 24/7 expert support
• Free email deliverability consultation 
• Generous free plan (up to 3,500 emails)
• Integration to MCP servers via Claude, Cursor, or VSC code editor.

Cons

• Email automation is available only via API, but a workflow builder is in beta.

Security

Both ESPs enforce TLS 1.2+; however, Mailtrap also supports MTA-STS, which offers slightly stronger protection. Additionally, Mailtrap gives you more granular control over API keys and monitoring.

Compliance

Both email services are similar compliance-wise, except Mailtrap’s SOC 2 certification is still in progress and its servers are in the US, although the platform itself is based in EU.

Pricing

Free plan: Up to 3,500 email sends per month (150/day)

I’d say Mailtrap’s pricing plans are quite scalable, with the Business tier having pretty much everything you need with a more-than-decent email limit. Check them out:

For more details, please consult the official Mailtrap pricing page.

Mailtrap vs Postmark pricing

Here’s how Mailtrap compares to Postmark in terms of email limits:

Key pricing differences: 

• The biggest difference between the two platforms is that with Mailtrap, you get dedicated IPs starting from the Business plan, whereas with Postmark, you need to be sending at least 300,000 messages a month just to be eligible for a $50 add-on. 
• Allowing you to send up to 3,500 emails per month (150 max daily), Mailtrap’s free plan is one of the most generous out there. Especially compared to Postmark’s free plan that lets you send 100 emails/month.
• Mailtrap doesn’t allow overages, whereas with Postmark, you can pay an additional 10k emails for $1.80, $1.30, or $1.20, depending on your plan.

P.S. If you’re looking to migrate from Postmark to Mailtrap, read our dedicated migration guide.

Customer experience

One of the first Mailtrap reviews I stumbled upon on Twitter was from a user who migrated from Postmark, saying that it’s a cheaper solution with better analytics and helpful customer support.

Reviews on Capterra and G2 were mostly positive, like the one in the screenshot below, with remarks on Mailtrap’s deliverability and dev-friendly API.

Mailchimp Transactional Email 

G2: 4.4 🌟 Capterra: 4.5 🌟

Mailchimp is one of the oldest names in the industry. It started out in 2001 as an email marketing platform, launched Mandrill as a transactional email add-on, has been acquired by Inuit, finally evolving into a full-fledged email delivery platform.

Now we have Mailchimp Transactional Email, a part of Mailchimp most suitable for small businesses on a budget who need both marketing features, on top of being able to send transactional emails.

Notable features:

• Pay as you go

When I say Mailchimp is most suitable for small businesses, it’s mostly because the platform offers a pay-as-you-go plan. You get all the essential features you need to start sending transactional emails. If you run out of them, you simply buy more credits.

Additionally, Mailchimp’s free plan is also generous in terms of the features it offers. Namely, you get limited email sends (1,000 per month and 500 contacts), but you can create surveys, landing pages, and more.

• Integrations

Mailchimp probably has the richest integration catalogue on this list, allowing you to connect your project to accounting tools, social media platforms, e-commerce shops, and more. 

There are two dozen categories you can use to sort through Mailchimp’s integrations, with some of them being available completely for free (e.g., Shopify, WooCommerce, Typeform, etc.).

• Email templates

Mailchimp offers more than 130 templates for all sorts of email campaigns. From basic newsletters and welcome emails to seasonal and announcement emails, you name it.

Additionally, if you have your own HTML emails you used at Postmark, you can import them to Mailchimp, edit them directly on the platform, and send them off.

How is Mailchimp different from Postmark?

Besides keeping your email logs for a shorter period of time than Postmark and having an email marketing suite, Mailchimp also provides AI tools, which Postmark doesn’t. Namely, Mailchimp has AI content helpers, optimizes sending times with AI, and even has predictive analytics.

Pros

• Drag-and-drop editor
• Automation templates
• SMS support
• AI email writer
• Onboarding help even on the free plan
• Pay as you go pricing

Cons

• Can become pricier, especially if you plan to send both transactional and marketing emails.
• When compared to other email service providers, especially Postmark, Mailchimp has a slightly higher learning curve due to its complex interface. 

Security

Here, Mailchimp offers broader API authentication with OAuth 2.0 and provides audit logs only for end-tier users, compared to Postmark, which enforces stricter access controls.

Compliance

In terms of compliance, Mailchimp is quite similar to Postmark, except that you cannot choose to send emails from Europe. 

Pricing

Free plan: 100 emails per month 

If you visit the Mailchimp pricing page, you’ll notice that it’s not as simple as Postmark. Namely, Mailchimp has separate pricing plans for its email marketing suite and for transactional email. 

Mailchimp Email Marketing

Mailchimp Email Marketing Plans are based on the number of contacts you have. Although I must note here that there is a significant increase in price if you have a big list, which is another reason I recommend Mailchimp for small businesses

Nonetheless, here are the price ranges you can expect:

For more details, please consult the official Mailchimp pricing page.

Mailchimp Transactional Email

For transactional emails, Mailchimp again lets you choose your sending volume and bases your final monthly subscription based off of that number. However, you don’t get any of the previously mentioned marketing features.

Here’s how it compares to Postmark:

Key pricing differences: 

• To get a dedicated IP from Mailchimp, you only pay an additional $29.95 per month and don’t have to send a certain number of emails to be eligible.
• Unlike Postmark, which offers 45-day email logs on all plans, Mailchimp limits them, along with advanced analytics, to higher-tier plans.

Customer experience

Users find Mailchimp a great option for small businesses, which is no surprise when you consider its pricing model.

Other users like its email marketing integrations, analytics, and dedicated support. However, there are some remarks about the template editor being clunky, which is a bit true since Mailchimp does have a tricky UI.

I have also found some friendly banter between the two yellow-heavy platforms on X:

Mailgun

G2: 4.2 🌟 Capterra: 4.3 🌟

Mailgun is a transactional email delivery service with SMTP and API solutions geared for developers.

Notable features:

• Rapid Fire Delivery SLA

For enterprise users, Mailgun offers Rapid Fire Delivery SLA, which comes with a promised 99.99% delivery rate even for volumes of 15,000,000 emails per hour. It’s also optimized for sensitive emails like 2FA codes or login links so that they’re sent with minimal latency.

Although this is one of Mailgun’s selling points for high-volume senders, it’s important to note that it doesn’t promise inbox placement, rather just the email handoff to the recipient’s server.

Interested in seeing how Mailgun performs without it? Here’s how it did compared to Postmark in our deliverability tests:

• Solid webhooks

Available on all plans, including the free tier, Mailgun’s webhook API can be configured to notify you of email deliveries, opens, bounces, etc. It’s also configurable at the domain level, which makes it a solid choice if you have multiple domains.

Additionally, Mailgun’s API has solid retry logic and will retry failed deliveries for up to 8 hours. This makes it quite reliable for tracking events and minimizing issues in cases where your server might be under a heavier load than usual.

• Email validation

Adding email validation logic to your web forms significantly reduces bounce rates and improves your list quality. Mailgun offers a validation API for this, which checks your new sign-ups for basic syntax errors, disposable addresses, typos, and more.

You get validation credits on all free plans, and you can pay $0.80 for additional validation charges.

How is Mailgun different from Postmark?

In contrast to Postmark, Mailgun offers a standalone testing/deliverability solution, Optimize. The suite includes the aforementioned validation API, has inbox placement tests, email previews, reputation & blocklist monitoring, Google Postmaster Tools integration, and more.

Mailgun also gives you more room for customization over your sending infrastructure than Postmark. Namely, you get full control over sending IP pools and domains, granular log retention, etc.

Lastly, if you want to spice up your email game a bit and launch a marketing campaign on top of sending transactional emails, you can integrate with Mailjet, which is a brand under the same Sinch roof.

Pros

• Developer-friendly
• High sending throughput
• Onboarding support
• Real-time tracking
• HIPAA support
• Inbound email routing support
• Marketing features via Mailjet integration

Cons

• Higher learning curve than Postmark, requires previous developer experience.
• A lot of useful features like deliverability consultation are locked to end-tier plans.

Security

While both platforms enforce strong encryption protocols and handle security well, I should note that Mailgun offers more granular API key management and user permissions. It also focuses more on reducing bounces and spam complaints, but those are just minor differences.

Compliance

The key difference here is that Mailgun supports HIPAA with a BAA, whereas Postmark does not. Besides that, both are similar compliance-wise:

Pricing

Free plan: 100 messages per day during the first month

Overall, Mailgun has a pretty basic pricing model, with several pricing plans with different sending limits and included features. So, the usual:

For more details, please consult the official Mailgun pricing page.

Mailgun vs Postmark pricing

Key pricing differences: 

• Although Mailgun has slightly more expensive plans in general compared to Postmark, it includes dedicated IPs once you get past 100k emails per month.
• Mailgun also offers a bunch of quality-of-life features in higher-tier plans, like link tracking, uptime SLA, dedicated IP warm up, and others.
• Mailgun has limited log retention for lower-tier plans, whereas Postmark gives you a full 45 days even on the starter plan.

Customer experience

I’ve noticed that Mailgun has mixed reviews on social media, but it seems to be praised by verified users on websites like G2 and Capterra. Its API gets a lot of love, and the fact that Mailgun helps you comply with inbox provider policies.

Others like its WordPress integrations, but are not the biggest fans of extended logs being available only to high-tier plans.

SendGrid

G2: 4.0 🌟 Capterra: 4.2 🌟

SendGrid is an email delivery platform that offers both an email API and SMTP for transactional email sending, as well as a suite of tools for sending email marketing campaigns.

Notable features:

• Deliverability features

SendGrid uses a cloud-based infrastructure, provides geo-specific IPs and reputation monitoring tools, Deliverability Insights for tracking email performance, and more. Overall, if you have a team of developers who can put these features to work, you won’t have to worry about deliverability much.

However, if you don’t use SendGrid’s deliverability features, here are the email placement results you can expect from it, especially if you’re on the free plan:

• Rich documentation

Even though SendGrid is not strictly geared for developers, like Mailgun, for instance, I have to admit it has super extensive documentation. It covers both transactional and email sending, has a plethora of examples and snippets, as well as quick-start guides.

• Email marketing suite

SendGrid covers all email marketing bases, from drag-and-drop editor and templates to marketing automation workflows and a wide range of integrations. 

However, I must note that you need to pay for a separate plan to use the email marketing features.

How is SendGrid different from Postmark?

The biggest difference between the two platforms is that Postmark doesn’t have email marketing features like drag-and-drop editor, automation workflows, and similar. However, when it comes to transactional email sending, both platforms do their job quite well.

You can also validate emails with SendGrid, whereas you cannot do so with Postmark.

Security

The only minor differences between the two platforms are that SendGrid offers MTA-STS whereas Postmark has more detailed activity logs and webhooks.

Compliance

When it comes to compliance, SendGrid and Postmark are pretty much on the same level.

Pros

• SMS support via Twilio
• Quality of life features
• Pre-warmed up IPs
• Global data centers
• Marketing tools
• Detailed analytics
• Plethora of integrations

Cons

• The free plan is a bit limited, but at least it’s not as limited as Postmark’s.
• Customer support is a bit limited, and you will get faster response times if you’re a Pro or Premier user.

Pricing

Free plan: Up to 100 emails per day for the first 60 days

SendGrid has two separate pricing models: one for its email API and one for its marketing campaigns. Considering you’re a Postmark user looking for an alternative, here’s SendGrid pricing plans for the platform’s email API:

For more details, please consult the official SendGrid pricing page.

SendGrid vs Postmark pricing

Key pricing differences: 

• SendGrid is a bit more expensive than Postmark but comes with more advanced features starting from mid-tier plans. These include SSO, deliverability optimization, dedicated IPs, etc.
• If you want to send more than 1 million emails per month, SendGrid is about $100 more affordable.
• Postmark gives you more teammates on lower-tier plans than SendGrid.

Customer experience

First, I must note that I’ve found concerning reviews for SendGrid on Trustpilot, where it has a staggering 1.1 out of 5 ranking. It’s mostly people giving it 1 stars with negative remarks on its customer support and account deletion, so be wary of that if you opt for SendGrid.

However, on other websites like G2 and Capterra, SendGrid has overall solid reviews, so I’m not sure if it’s an issue with Trustsend. For instance, people praise the platform’s API and how it helped them reduce bounce rates.

Other users remark that SendGrid’s SMTP is easy to set up and that they’re achieving high deliverability rates.

Amazon SES

G2: 4.3 🌟 Capterra: 4.7 🌟

Amazon SES (Simple Email Service), is a cloud-based email service provider for experienced developer teams who are already in the AWS (Amazon Web Services) ecosystem.

Notable features:

• Amazon infrastructure

Being a part of the AWS ecosystem, Amazon SES has a rock-solid infrastructure based on cloud-native architecture. All the technical jibber-jabber aside, this means you don’t have to worry about hiccups during email spikes, downtimes, or anything of the sort.

More importantly, Amazon SES scored quite well compared to Postmark on our deliverability tests:

• CloudWatch and Virtual Deliverability Manager (VDM)

Although Amazon SES doesn’t offer native analytics for tracking important deliverability metrics, you can either integrate it with Amazon CloudWatch or use the Virtual Deliverability Manager (VDM).

This way, you get in-depth analysis of the performance of your emails, and you can even go as far as creating custom dashboards and notifications.

Source: Amazon SES

• AWS integrations

Besides CloudWatch and VDM, you can also integrate SES with a plethora of other AWS integrations. This gives you plenty of room to customize your sending experience, but requires some technical expertise.

For instance, you can use Amazon SNS (Simple Notification Service) to trigger alerts when your recipient’s domain starts rejecting your messages for some reason. Or, you can route bounce or delivery notifications to take further action, like removing invalid addresses or recipients.

Some other useful AWS integrations include: Amazon S3, Lambda, and EventBridge.

How is Amazon SES different from Postmark?

The biggest difference between the two is that Postmark is an out-of-the-box solution requiring minimal setup for you to start sending emails with it. 

More specifically, with Postmark, you can just register, verify your domain, copy/paste the code snippet for your preferred language or framework, and start sending.

On the other hand, Amazon SES requires an initial setup and previous AWS knowledge for you to start sending. However, if you have experience, I’d say this is a benefit over Postmark, since SES gives you plenty of room for configuration. You can select IP pools, play around with suppression rules or event archiving, and the list goes on.

Security

Amazon SES is as secure as it gets since it offers native AWS controls like IAM policies, MFA, and extensive logging via CloudWatch and CloudTrail. It’s also highly customizable and supports both opportunistic and forced TLS with optional MTA-STS.

Compliance

The main difference between Amazon SES and Postmark compliance-wise is that the former supports HIPAA, whereas the latter doesn’t. Also, SES uses CloudTrail for logging.

Pros

• Integration with AWS
• Reputable IPs
• Solid webhooks
• Super affordable
• Generous free plan
• Inbound email support

Cons

• A steep learning curve that requires you to be at least familiar with the AWS console. 
• Expert deliverability support is only available at the enterprise-level AWS plan.

Pricing

Free plan: Amazon SES offers 62,000 emails for free if you’re using Amazon EC2 and AWS Elastic Beanstalk.

Amazon SES offers one of the most affordable SMTP/API services on the market, and the simplest one at that, too. Namely, you pay $0.10 per 1,000 emails. That’s it, that’s the whole philosophy behind it.

If you’re interested in more numbers, here’s how it fares against Postmark:

Key pricing differences: 

• To use Postmark, you need to pay at least $15/month for 10,000 emails. With Amazon SES, there is no minimum monthly spend.
• Managed dedicated IPs at Amazon SES cost $15/month per account, whereas standard ones cost $24.95/month per IP, which is more than 3 times cheaper than Postmark.
• You can also pay $24.95 per month for a Bring Your Own IP Address (BYOIP)

For more details, please consult the official Amazon SES pricing page.

Customer experience

As I had expected before digging into online SES reviews, users seem to love its pricing model and the low cost. Additionally, a lot of users are well aware of the steep learning curve.

On X, I’ve found a few users who were not satisfied with Postmark since its acquisition by Active Campaign, its increases in pricing, and issues with transactional email sending. In the threads, other users seem to recommend Amazon SES as a solid alternative.

Brevo

G2: 4.5 🌟 Capterra: 4.6 🌟

Brevo is a five-in-one platform for relationship marketing that, besides SMTP and email API services, also offers a rich email marketing suite. This makes it a solid choice for teams looking to send email campaigns on top of their user-triggered, transactional emails.

Notable features:

• Newsletters

Looking to spice it up and launch newsletter campaigns on top of your transactional emails? If so, you can use Brevo’s free newsletter software that includes a drag-and-drop editor, 40+ newsletter templates, AI writing assistance, and real-time analysis of the campaign performance.

Speaking of newsletters, Brevo also offers a vast collection of email templates, good-looking ones at that, too.

• Automations

If you want to automate your email marketing workflows, look no further than Brevo’s automation builder. It’s super simple to use, has everything you need in one place, and there are even templates you can use. I should also probably note that both the builder and the templates are available even for the free plan users.

•  Integrations

From integrations with CRM platforms like Salesforce and HubSpot to CMS integrations with Webflow or Wix, Brevo has them all. Well, not all of them, slightly over 150 to be more precise. Nonetheless, if you’re looking to connect your app/project with a certain platform, check out Brevo’s app marketplace to see if it has the supporting integration.

How is Brevo different from Postmark?

The major difference between Brevo and Postmark is that the former is a full-featured email marketing platform, whereas the latter is a transactional messaging service focused on speedy delivery of user-triggered emails.

With Brevo, you can create automations, send SMS campaigns, create emails with a drag-and-drop editor, and, on top of all that, integrate its SMTP or API with your app/project.

Also, even though it’s more of an email marketing campaign than a transactional email provider, Brevo still offers extensive documentation and supports major programming languages. However, I have to note that Brevo doesn’t offer any pre-made code snippets for its SMTP.

Pros

• Easy to use
• Useful integrations
• Solid customer support
• Clear API documentation
• Email templates
• SMS, WhatsApp, and push notifications support
• Webhooks for transactional and marketing events
• Contact list segmentation and management

Cons

• You can have multiple users only on Business and Enterprise plans.

Security

In terms of security, Brevo matches Postmark on major standpoints like encryption and authentication. However, it falls short on logging and email alerts.

Compliance

Although it lacks SOC 2 certification and the fact that logging is available only on request, Brevo is quite on par with Postmark in terms of compliance.

Pricing

Free plan: 300 emails per day

Brevo has quite a generous pricing model, offering all users with more than 10,000 monthly email sends unlimited contacts, as long as they stay within their Fair use limit. The limit is as follows:

• Starter plan: 100.000 emails and 500,000 contacts
• Business plan: 1.000.000 emails and 2,000,000 contacts

It’s also important to note that if you exceed these limits, Brevo might enforce restrictions on your account or ask you to upgrade your plan. And here’s what the plans offer:

For more details, please consult the official Brevo pricing page.

Brevo vs Postmark pricing

Key pricing differences:

• One of the most noticeable differences is that to remove Brevo branding, you have to pay $10-12 per month.
• Brevo also offers dedicated IPs as add-ons, but they’re more affordable than Postmarks, coming with the price of $251 per year, compared to Postmark’s $50/month.

Customer experience

When I was going through online Brevo reviews, I was happy to see that other people also recognized the platform as having solid templates, segmentation, and managing marketing and transactional emails.

There were also a bunch of positive remarks for Brevo’s customer support team, like this one, for example:

Wrapping up

If you’ve made it this far, I congratulate and thank you for your patience!

Hopefully, you’ll go with Mailtrap after reading this article, but if it doesn’t seem like the right choice for you, feel free to try out other Postmark alternatives I listed. 

And if you feel like exploring some other options, check out our blog, where you can find articles such as:

• SMTP Providers Compared
• 7 Best Transactional Email Services
• Free Email Marketing Platforms
• Mass Email Services Reviewed

Anyway, with this SMTP providers’ security comparison, I’m dissecting the security postures of some of the industry’s leading SMTP services to help you make an informed decision. 

My goal is to equip you with the knowledge to choose a provider that sends your emails while safeguarding brand communications and integrity.

SMTP providers security comparison: a snapshot

Check the quick overview of the key players in this SMTP providers security comparison. I have to stress that all providers essentially offer the same security levels and follow all protocols. The choice lies in other factors such as overall features, pricing, workflows, etc.

Also, the providers best cater to slightly different audiences, so the quick list below focuses on that. 

• Mailtrap – Best for product companies sending at a high email volume.
• Mailgun – Best for developers.
• SendGrid – Best for businesses that need transactional and marketing emails.
• Amazon SES – Best for experienced dev teams.
• Postmark – Best for dev teams, particularly those focused on transactional emails.

Here’s a glance at how these providers stack up across the most important security features. I’ll explore each of these in much more detail shortly. You can use the table to jump to the sections that are of your interest.

Continue reading for a full breakdown of what these short descriptions mean and their implications for your email security.

Methodology

I combined rigorous research with a conceptual (and practical) understanding of hands-on security testing to deliver an accurate and comprehensive SMTP provider security comparison. 

🔽Check the categorized methodology breakdown below. 🔽

Documentation research

My primary resource was the official documentation provided by each SMTP service to gauge how far they support zero-trust security principles and provide end-to-end email encryption (beyond the now obsolete SMTP AUTH).

I delved deep into:

• Security docs: Official statements on policies, compliance (e.g., ISO 27001, SOC 2), and infrastructure security.
• Header security: Analysis of common email headers for security indicators like Authentication-Results, Received, and ARC-Authentication-Results.
• SMTP behavior guides: How each provider handles SMTP commands, error codes, and connection parameters.
• IAM/API setup: Documentation on managing user access, API keys, and their respective permissions.
• DNS requirements: Information on setting up SPF, DKIM, DMARC, and MTA-STS records.

Hands-on testing (Conceptual)

I didn’t perform live, real-time penetration testing for this comparison; my analysis is informed by how such tests would reveal security postures. This includes conceptual evaluations of:

• TLS negotiation tests: Verifying the minimum TLS versions enforced (TLS, TLS-RPT, and STARTTLS) and the cipher suites supported by their SMTP endpoints.
• SMTP command probing: Observing how services respond to malformed or unexpected SMTP commands, which can reveal robustness.
• API key generation and scope: Assessing the granularity of permissions that can be assigned to API keys and the ease of revoking/managing them.
• IP locking/restriction: How effectively providers allow users to restrict API or SMTP access to specific IP addresses.
• Header injection handling: How providers sanitize or prevent malicious header injections that could lead to spoofing or information disclosure.

Note: I want to stress that this conceptual testing was a team effort, combining my experience with that of our in-house deliverability expert, security team, and developers working on Mailtrap’s email infrastructure. 

SMTP providers security detailed comparison

Now, let’s get into the granular details of each security aspect, how the providers stack up, and what it means for your operations.

I’ll be doing side-by-side comparisons focusing on the security vertical covered in each section. 

SMTP server encryption and transmission security

Encryption and transmission security define how your emails are protected while in transit from your application to the SMTP provider, and from the provider to the recipient’s mail server. 

Key aspects include:

• The enforcement of TLS (Transport Layer Security) protocols 
• The adoption of modern standards like MTA-STS (Mail Transfer Agent Strict Transport Security). 

Pro tip: Take the time to set up BIMI (Brand Indicators for Message Identification). It helps with security, recipient trust, and overall email deliverability.

Without robust encryption, sensitive information in your emails could be intercepted.

Meaning within test: I looked for explicit statements on enforced TLS versions (e.g., TLS 1.2+), support for Opportunistic TLS, and crucially, the availability and ease of configuring MTA-STS. MTA-STS prevents downgrade attacks and ensures that connections between supporting mail servers are always encrypted with TLS.

The result interpretation:

All providers in this comparison utilize TLS for email transmission, which is foundational.

However, the nuance lies in enforcement and MTA-STS. Mailtrap, Mailgun, SendGrid, and Postmark make it straightforward to ensure your outbound emails use a strong TLS version.

Amazon SES, on the other hand, offers opportunistic TLS by default, but you can enforce higher TLS versions for specific destinations, which requires a bit more configuration.

For large-scale senders dealing with sensitive data, MTA-STS is paramount. It tells recipient servers to only accept TLS-encrypted connections from your domain, mitigating man-in-the-middle attacks.

Providers that offer clear guidance or automated setup for MTA-STS (like Mailtrap) gain a significant security advantage, especially for businesses with high-value communications.

Further reading: 25, 2524, 465, 587, and Other Numbers: All About SMTP Ports

Authentication and identity control

Authentication and identity control cover mechanisms that verify your identity as an email sender and prevent unauthorized parties from spoofing your domain. They’re crucial for deliverability; and protect your brand reputation against phishing and spam. 

Key technologies include SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance).

Meaning within test: I assessed the ease of setting up SPF, DKIM, and DMARC records, the clarity of instructions, and whether the provider supports advanced features like custom MAIL FROM domains. 

The result interpretation:

All secure SMTP providers facilitate the setup of SPF, DKIM, and DMARC, which are non-negotiable for senders at any volume.

The main differentiator lies in the clarity of the setup process and additional features. Mailtrap, Mailgun, SendGrid, and Postmark offer straightforward interfaces for adding these records.

Pro tip: Don’t be surprised by any additional verifications during the DNS setup, these are the standard protocols to ensure your infrastructure is secure.

Amazon SES also provides excellent guidance, but it’s more technically demanding.

For large organizations, ensuring robust DMARC policies is critical for combating impersonation. While DMARC reporting isn’t typically handled by the SMTP provider directly, each provider ensures the necessary headers are present for third-party DMARC monitoring services.

A custom MAIL FROM domain, supported by all, further enhances authenticity and can improve deliverability.

API and credentials security

API and credentials security signal how safely you interact with the SMTP provider’s API for sending emails, retrieving logs, and managing settings. That includes how API keys are generated, stored, and protected from unauthorized use. Compromised API keys can lead to spam, data breaches, and significant reputational damage.

Meaning within test: I looked for features like granular API key permissions, IP address whitelisting for API access, and the ability to easily revoke or rotate keys.

The result interpretation:

The ability to generate granular API keys is a major security advantage, especially for teams. Mailtrap, Mailgun, SendGrid, Postmark, and Amazon SES all offer this, but the level of granularity varies.

Amazon SES, leveraging AWS IAM, provides the most flexible and detailed control over API access, though, as I mentioned quite a few times before, it is more complex to set up.

IP whitelisting for API access is a critical feature that all these providers offer, acting as a strong barrier against unauthorized access even if a key is compromised.

Account access and user controls

Account access and user controls focus on security measures that protect your account from unauthorized access and ensure proper internal governance. They include features like Multi-Factor Authentication (MFA), Single Sign-On (SSO), and Role-Based Access Control (RBAC).

Meaning within test: I examined the availability and implementation of MFA, SSO capabilities (particularly for enterprise and lower plans), and the flexibility of user roles and permissions within the platform.

The result interpretation:

MFA is a fundamental security requirement and all providers here offer it.

To stress, for larger organizations and enterprises, RBAC allows administrators or account owners to assign specific permissions to different team members, limiting exposure and adhering to the principle of least privilege. In turn, you get a much more secure email infrastructure.

Amazon SES, through AWS IAM, provides the most comprehensive RBAC system, aligning with broader AWS security practices. SSO simplifies user management and enhances security by centralizing SMTP authentication.

To the above, audit logs are vital for forensics (e.g., a postmortem) and compliance, providing a clear trail of all actions performed within the account. Mailtrap, for example, offers robust audit logging, providing transparency for your team’s activities.

Abuse prevention and misuse protection

Abuse prevention and misuse protection address how the SMTP providers actively work to prevent spam, phishing, and other forms of email abuse originating from or targeting your account. This is crucial for your reputation and the overall health of the email ecosystem.

Meaning within test: I looked for features like real-time threat detection in email delivery, automated bounce handling, complaint feedback loops, and general reputation management tools.

The result interpretation:
All leading SMTP providers invest heavily in abuse prevention. They all process bounces and complaints, automatically suppressing bad addresses to protect your sender reputation. The key difference often lies in the proactiveness and visibility they offer.

Mailtrap, for instance, doesn’t just handle issues but provides the insights to prevent them.

In contrast, services like Amazon SES provide detailed reputation dashboards.

For high-volume senders, understanding and acting on bounce and complaint data is paramount to maintain healthy deliverability. Otherwise, the senders reputation could drop fast just based on the sheer volume they handle.

Therefore. robust internal spam filtering on the provider’s side prevents your account from being flagged or exploited.

Security event logging and notifications

Security event logging and notifications refer to the ability to monitor security-related events within your SMTP account and receive timely alerts for suspicious activities or critical incidents. Comprehensive logs are essential for auditing, troubleshooting, and forensic analysis.

Meaning within test: I assessed the depth and retention of event logs, the types of events recorded (e.g., login attempts, API calls, setting changes), and the availability of notification mechanisms (e.g., email alerts, webhooks).

The result interpretation:
For large organizations and those with strict compliance requirements, detailed security event logging and robust notification systems are critical.

All providers offer some form of logging, but Amazon SES, integrated with AWS CloudTrail and CloudWatch, provides an incredibly deep and customizable logging infrastructure, albeit with a steeper learning curve.

Mailtrap, Mailgun, SendGrid, and Postmark offer user-friendly activity feeds and webhook capabilities for real-time notifications. The ability to receive alerts for suspicious login attempts, API key usage, or sudden spikes in sending is invaluable for proactive security and vulnerability management.

Wrapping up

Choosing an SMTP provider isn’t just about deliverability; it’s profoundly about the security of your entire email infrastructure. This goes double if you operate in heavily regulated industries.

As this SMTP providers security comparison highlights, all leading services offer a baseline of secure email delivery, including features like TLS email encryption and SPF/DKIM/DMARC support. 

But the nuances in their implementation, advanced features like MTA-STS, granular API key security and control, and robust auditing capabilities can make a significant difference.

For product companies  and large-scale senders, Mailtrap stands out by integrating a secure and reliable sending platform with a comprehensive testing environments with, emphasizing developer-centric features that inherently improve security posture. 

So, go ahead, give it a try.

So, I’ve spent the past few weeks going through the haystack of email APIs, then I reviewed the best of them and compiled a nice little list to help you choose the best one for your needs.

Before we dive in, if you feel like freshening up or fine-tuning your knowledge, you can check out the article our email infrastructure expert, Dzenana, has written on email APIs.

Best email API: a snapshot

Click on a platform name to jump ahead to the detailed review.

• Mailtrap is best for high-volume product companies that are looking for high deliverability rates, in-depth analytics, and growth-focused features.
• Mailgun is best for developers with in-depth email sending expertise who need detailed logs and an email validation API on top of an email API.
• SendGrid is best for enterprise users who need granular control over their user permissions.
• Amazon SES is best for current AWS users who have extensive experience with setting up, configuring, and supporting email infrastructures.
• Postmark is best for teams looking to send transactional emails and don’t need any extra features.

I’ve made a chart to help you compare the APIs you might be leaning towards. Check it out.

Disclaimer: The ratings, features, and prices are up-to-date as of writing this article, but they could be different when you’re reading it, as they’re prone to change.

Email API providers comparison methodology

To bring you an unbiased, accurate, and comprehensive review of the best email API providers, I conducted a thorough research and tested (almost) everything they offer.

However, I must note that I didn’t conduct the research alone, since I had the help of Mailtrap deliverability experts, security team, and developers who work on our infrastructure.

Documentation research

First and foremost, I made sure to dig through each provider’s:

• Official API docs to see how easy to integrate for your team an API is and what it offers (e.g., sending endpoints, bounce handling, templates, etc.).
• GitHub repositories to check whether an API is being regularly maintained and updated.
• Testimonials and reviews to see what a provider’s user base thinks and how the APIs hold up compared to advertisements. 
• Knowledge bases and blogs to look for helpful guides and tutorials on setting up and using an API.

Hands-on testing

Recently, over at Mailtrap, we conducted a thorough email API flexibility research where we:

• Sent emails with different sending configurations to test real-world use cases such as sending attachments and bulk emails, etc.
• Triggered API rate limits and retry behavior to inspect how an API handles high volume, throttling, and retries.
• Created email templates to evaluate how much personalization each API allows and to test templating logic and dynamic content.
• Set up webhooks for some of the events they support to see how quickly you get automated notifications about the most important metrics like bounces.

Now, let’s get on with the reviews of each email API provider or check out the detailed criteria first by clicking on this jump link. 

Best email API for high deliverability & flexibility: Mailtrap

G2: 4.8 🌟 Capterra: 4.8 🌟

Mailtrap Email Delivery Platform is designed for developer and product teams with high sending volumes that need high deliverability rates, in-depth analytics, and growth-focused features. 

Additionally, Mailtrap offers one of the most flexible email APIs out there that allows developer teams to fine-tune their sending configuration according to their specific needs. Of course, I would never claim this without being able to back it up.

Recently, we’ve performed numerous tests with the top APIs in the industry, simulating real-world usage to see how much control the user gets. Here’s a table that summarizes key findings of our research:

To learn more about our methodology and get more in-depth information on technical tidbits like IP infrastructure, throttling, retry mechanisms, etc., read our full comparison. 

Why is it the best email API?

• High deliverability

Mailtrap uses separate sending streams, dedicated IP addresses, email warm-up, throttling, and other advanced features to help all of its users achieve high deliverability rates, regardless of the plan. 

The platform also has a team of deliverability experts at its users’ disposal, who can help you with any deliverability-related issues you might face.

Moreover, we’ve recently performed several deliverability tests with top API providers. To make sure the tests were fair to everyone, we used free plans, didn’t warm up domains, used the same template, etc. 

Here’s how Mailtrap performed:

• In-depth analytics

With Mailtrap, you can keep an eye on the performance of your email campaigns thanks to helicopter view dashboards and drill-down reports. These let you track email metrics like opens, clicks, bounces, and others. 

Additionally, Mailtrap will keep your email logs for up to 30 days,

• Email templates

Besides the drag-and-drop email builder, which can make your marketers’ lives easier, Mailtrap offers an HTML editor your devs can use to create email templates from scratch.

The templates use the Handlebars engine with which you can set up additional variables and conditional variables like if and else statements to automate a big portion of your sending workflow.

Pricing

Mailtrap offers several different scalable plans and has one of the most cost-effective email APIs since it doesn’t keep customer support or high inboxing rates locked away for higher tiers.

As of writing this article, the most popular plan is Business 100k, being in the golden middle and offering a plethora of advanced features with 100,000 monthly emails at an affordable rate.  

Here’s a quick table that sums the pricing plans up:

For more details, please consult the official Mailtrap pricing page.

Pros

• High deliverability rates
• Separate sending stream
• Industry-best analytics
• Advanced webhooks
• GDPR compliant
• ISO/IEC 27001:2022 certified 
• 24/7 expert support
• Free email deliverability consultation 
• Extensive API documentation
• Email marketing suite
• Integration to MCP servers via Claude, Cursor, or VSC code editor.

Cons

• Currently, you can only integrate Mailtrap with services such as Zapier and Tabular email, but more integrations are on the way.
• Automations are still in alpha but the official release is planned for the near future.

Developer experience

Official API documentation

Mailtrap offers easy-to-use SDKs for Node.js, PHP, Ruby, Python, Elixir, and Java.

It offers code snippets for major programming languages, which lets you start sending emails right away. All you need to do is copy/paste the provided script into your sending configuration, insert your credentials, and you’re off.

Here’s a Node.js code snippet offered by Mailtrap:

const Nodemailer = require("nodemailer");
const { MailtrapTransport } = require("mailtrap");

const TOKEN = "<YOUR_API_TOKEN>";

const transport = Nodemailer.createTransport(
  MailtrapTransport({
    token: TOKEN,
  })
);

const sender = {
  address: "hello@demoatmailtrap.com",
  name: "Mailtrap Email",
};
const recipients = [
  "demo@mailtrap.io",
];

transport
  .sendMail({
    from: sender,
    to: recipients,
    subject: "You are awesome!",
    text: "Congrats for sending an email with Mailtrap!",
    category: "Integration",
  })
  .then(console.log, console.error);

The documentation is also quite extensive, regularly updated, and has everything you need in one place.

Additionally, Mailtrap has a blog with step-by-step articles on setting up the platform’s SMTP/API and sandbox with all major programming languages and web dev frameworks, such as:

• How to Send Emails in Java
• How to Send Emails in C#
• How to Send Email in Python

On top of that, their YouTube team has been busy and provided a lot of follow-along videos on setting up sending functionality, validation mechanisms, and more. Check it out.

Security 

From email authentication to detailed logs and monthly DKIM key rotation, Mailtrap has every security element covered:

Compliance

Mailtrap is compliant with all modern regulations, it’s ISO certified, and SOC 2 certification is in progress:

Testimonials

While scouring online reviews, I’ve noticed that Mailtrap is praised for its deliverability and dev-friendly API. One of the reviewers also mentioned how the Mailtrap support team helped them resolve DKIM alignment issues within a few hours:

Others like its API for its reliability and rapid delivery time:

Best for advanced email devs: Mailgun

G2: 4.2 🌟 Capterra: 4.3 🌟

Mailgun is a transactional email service that provides an SMTP and email API designed for developers. 

Here’s a quick breakdown of its most important features:

Why is it the best for advanced email devs?

• Webhook API

Mailgun’s webhook API can be supported at the domain level, which can be handy if you’re using multiple domains. Additionally, it supports many engagement events, such as accepted, delivered, spam complaints, and more.

If a webhook delivery fails, Mailgun will retry the delivery for up to 8 hours.

• Email validation API

If you want to add email validation logic to your web forms, you can do so with Mailgun’s email validation API. Besides the basic syntax and DNS checks, Mailgun cross-references your email list against its database of 450 billion emails, and warns you about high-risk addresses.

You can also validate your contacts in bulk if you don’t feel like integrating.

• Detailed email logs

Mailgun keeps your email logs for up to 30 days, but that’s not their biggest selling point. Namely, what makes them great is the fact that there are 10 filter fields you can use to customize your logs and then analyze them across all your domains.

These include TO and FROM headers, event types, list names, tag names, and others.

Pricing

Mailgun has a generous free tier that lets you send 5,000 emails during the first month, which would make it perfect for startups if it didn’t lock away some important features like dedicated IPs to high-tier plans. Nonetheless, here’s a brief summary of its pricing:

For more details, please consult the official Mailgun pricing page.

Pros

• High throughput
• EU and US data centers
• Rapid Fire Delivery SLA
• Email validation
• Onboarding support
• Real-time tracking
• Solid webhooks
• Inbound email processing

Cons

• Only the highest-tier plan, Scale, offers 30 days of email logs.

Developer experience

Official API documentation

Mailgun supports Python, Go, Node.js, PHP, Java, and Ruby.

The email platform has a dedicated developer documentation page, which you can use to inspect any of its 4 APIs. The page layout is super clear, and navigating is a breeze, making it great even for junior developers. Night mode is also a big bonus.

The code snippets Mailgun provides aren’t as extensive as they come, but the platform has a nice blog where you can find some solutions to several programming languages. 

Security

Mailgun’s focus is on granular user permissions, has all encryption check boxes cleared, and is quite a secure API:

Compliance

Mailgun is compliant with GDPR, stores its data in the EU, and is compliant with all of the latest regulations. You can get more info on the compliance and security page or check out the summary table below:

Testimonials

Overall, although it has its issues, Mailgun has solid ratings on review websites. A reviewer that stood out to me praised Mailgun’s API and the email platform’s ability to help their company comply with inbox provider policies for Google, Microsoft, and Yahoo:

I also found a short case study, describing how a Ruby-based company, DNSimple, used HTTParty to integrate with Mailgun API, then programmatically created and configured domains, set up forwarding routes based on regex, and more.

Best for enterprises: SendGrid

G2: 4.0 🌟 Capterra: 4.2 🌟

SendGrid is one of the oldest names in the industry, providing an email API and SMTP service most suitable for enterprises due its high level of multitenancy support.

Although it doesn’t offer a separate sending stream, SendGrid’s API is overall flexible:

If you’re interested, check out how SendGrid compares to Mailtrap.

Why is it the best for enterprises?

• Subuser accounts

If you own a multi-brand business, or an agency that has different clients, or if you simply need granular permission control, SendGrid lets you segment your sending and email API activity.

Namely, you can create subusers with specific permissions, give each user credit limits, etc. For example, you can set it up so that one user can only send transactional emails while another can send only bulk.

Most importantly, each subuser will have separate API credentials, stats, and sender reputation.

• IP pool management

With SendGrid, you can assign dedicated IPs to different email types or group them together for better deliverability and sender reputation. 

Additionally, SendGrid offers IP Access Management, a strong security feature that lets you control who can access your account based on their IP address. 

• Deliverability features

To help you ensure your emails land in main inboxes, SendGrid uses a cloud-based infrastructure and offers everything from warmed up geo-specific IPs to reputation monitoring and adaptive throttling and optimization.

You can also use SendGrid’s Deliverability Insights with its email API and webhooks to receive real-time notifications on key performance metrics.

Pricing

SendGrid has straightforward pricing plans, although they can ramp up in cost if you intend to use the platform’s advanced features like dedicated IPs or have extra slots for teammates:

For more details, please consult the official SendGrid pricing page.

Pros

• Pre-warmed up, geo-specific IPs
• Quality of life features
• Good documentation
• Granular user control
• Onboarding assistance
• Long webhook retry windows
• SMS support via Twilio
• CRM support and integrations with other useful platforms

Cons

• Dedicated IPs and reverse DNS are available only to high-tier users.
• Slightly steeper learning curve since it’s geared towards developers.

Developer experience

Official API documentation

SendGrid supports C#, Go, Java, Node.js, PHP, Python, and Ruby.

The platform’s API documentation is pretty clear and has everything you need, although I especially liked the onboarding guide, which you can follow step-by-step when integrating the API.

There are also code snippets for everything, so your developers will have to spend minimal time coding.

The platform’s customer support team is also available via ticket, chat, and phone, although it’s locked to higher-tier plans.

Security

Besides offering detailed IP access management, SendGrid covers all security bases: 

Compliance

With SendGrid, you can choose whether you want to send your emails from EU or US, which allows you to deliver them faster. Besides that, it’s compliant with all of the important regulations:

Testimonials

Although I’ve noticed people aren’t big fans of SendGrid’s customer support on social media and ratings websites, they seem to be pretty satisfied with the email sending service API. More specifically, with how easy it is to integrate it:

However, I’ve noticed the opposite on Capterra, so you be the judge:

Best for AWS users: Amazon SES

G2: 4.3 🌟Capterra: 4.7 🌟

Amazon SES, short for Simple Email Service, is a cloud-based email API provider that’s geared towards developer teams who are already using AWS and have technical expertise.

As for the flexibility aspect of Amazon SES, here’s a summary table:

Why is it the best for AWS users?

• AWS integration

As part of the AWS Global Infrastructure, Amazon SES can be integrated with various AWS services. Some of these include S3, Lambda, SNS Support, and others.

Although this can streamline a lot of workflows, I must mention that it requires technical expertise. 

• Identity and access management

With AWS Identity and Access Management (IAM), you can fine-tune your permissions based on users, roles, or systems. This allows you to manage your API key authentication and management, separate access between clients or environments, and more.

• CloudWatch monitoring

Another useful AWS integration is Amazon CloudWatch. By integrating Amazon SES with it, you can get metrics on email sends, bounces, spam complaints, rejects, and rendering failures.

You can also create custom dashboards to visualize your email delivery performance or even set alarms to get notified when a certain metric exceeds a threshold (e.g., when your bounce rate goes above 5%).

Pricing

Amazon SES has a super simple pricing model: you pay $0.10 per 1,000 emails, which equals $1 for 10,000 emails or $10 for 100,000 emails.

Moreover, if you’re using Amazon EC2 and AWS Elastic Beanstalk, you get the first 62,000 emails for free.

For more details, please consult the official Amazon SES pricing page.

Pros

• Integration with AWS
• Super configurable
• Secure and compliant
• Strong and reputable IPs
• A/B testing
• Solid webhooks support
• Has servers in EU, US, and Asia
• Scalable and affordable pricing model

Cons

• Doesn’t have an in-built native analytics UI, so you need to integrate with a 3rd party service instead.
• Requires coding experience and being comfortable with the AWS ecosystem to be used to its 100%.

Developer experience

Official API documentation

Amazon SES has official libraries for Java, .NET, PHP, Python, Ruby, and Go.

Although Amazon SES has robust documentation, I have to note that you also need a little bit of developer experience, as well as experience with the AWS ecosystem. This is especially true if you want to use the API to its fullest potential.

For example, using Amazon SES API to send emails requires you to verify your domain, move out of the SES sandbox mode since all accounts start in it, create IAM credentials, configure permissions, and only then install an AWS SDK and set up your credentials. See what I mean?

Security

Being a part of the Amazon Infrastructure, it’s safe to say that you don’t have to worry when it comes to Amazon SES and security:

Compliance

Similarly, Amazon SES covers all bases when it comes to compliance, even offering servers in Asia:

Testimonials

One of the most common remarks I’ve seen about Amazon SES is that it’s affordable:

I’ve also found many reviews that say Amazon SES is for developer teams experienced with AWS configurations, although they don’t like the fact that you need 3rd party integrations for analytics:

Best for separate streams: Postmark

G2: 4.6 🌟 Capterra: 4.9 🌟

Postmark is an email platform that provides a transactional email API service for developers. 

It’s API is flexible, giving you room to play around with your infrastructure:

Why is it the best for separate streams?

• Separate sending streams

Postmark offers separate sending streams, similar to Mailtrap. The streams are dedicated to bulk emails (Broadcast Message Stream) and user-triggered emails (Transactional Message Stream).

Furthermore, you can create a custom stream for specific email types. So, for instance, you can create a separate stream for password reset emails, a separate one for invoices, etc.

• Detailed event logs

With Postmark, you get to keep your email logs for up to 45 days, and they’re really detailed. 

You can filter the logs by status, subject, custom tags, and date. They’re also quite configurable. For example, you can configure them so you retrieve them automatically via Postmark’s Message API or even connect webhooks with them.

• Transactional email templates

Welcome emails, receipts, invoices, user invitations, trial expirations; you name it. With Postmark Email Templates, you can create all kinds of designs for your app/project, and then send them when they’re ready via Postmark API.

The templates are powered by Mustachio, a lightweight templating engine that allows you to make dynamic email content. 

Pricing

Ever since its price increase in 2025, Postmark has been on the more expensive end, but nonetheless, it’s still more affordable than a lot of its competitors (looking at you, Mailchimp):

For more details, please consult the official Postmark pricing page.

Pros

• Straightforward setup
• Separate sending streams
• Fast email delivery
• Transparent deliverability status
• Inbound email support
• Logs for up to 45 days
• Real-time notifications with webhooks
• Offers MCP agents 

Cons

• You can reach Postmark customer support only via tickets and it’s not available 24/7.
• To get dedicated IPs, you need to be sending at least 300,000 emails per month.

Developer experience

Jump to: Official API documentation

Postmark has official libraries for Ruby, RoR, .NET, Java, PHP, and Node.js.

The platform’s documentation is also very well organized, and it seems to be regularly updated. In translation: you don’t even need to be as experienced to use Postmark’s email API and start sending emails. 

Speaking of email sending, you get code snippets for every major programming language and web framework Postmark supports:

Security

The aspect I liked the most about Postmark’s security is the way it automatically blocks delivery for bounces and how detailed its activity logs are. It also has all important encryption protocols in place:

Compliance

Besides allowing you to choose whether you want EU or US hosting, Postmark complies with key industry standards and certifications:

Testimonials

Generally, people like Postmark’s SMTP and API for sending transactional emails, although I’ve noticed that some have an issue with the platform’s customer support team not working around the clock and having only ticket support:

On the other hand, some people like the fact that Postmark supports whitelabel domains and has solid deliverability:

If you’re interested in exploring what Postmark users have to say about the platform and its API, you can also check out its customers page. 

Transactional email API comparison criteria

To select the best email API on the market, I used the following criteria:

Email infrastructure

When talking about email infrastructure, we are actually talking about the following aspects:

Deliverability

Email APIs with high deliverability rates are more likely to send your emails to your recipients’ inboxes, instead of delivering them to the spam folder. 

However, as the exact rates are not publicly available, we’ve run a few deliverability tests for some of the providers on the list. And yes, the tests were fair for all email API providers: we made sure to use a free plan, shared IP, the same template, and no domain warmup. 

Here are the results (other providers’ results are on the way):

For the full results and insights into the methodology we used, check out our dedicated blog post on email deliverability comparison.

Reliability & uptime

As far as reliability goes, an ideal email API is one with the least amount of downtime and always-ready customer support. So, I’ve scoured the web looking for downtime reports and checked out each API’s customer support availability.

To take it one step further, I’ve checked out various status pages like this one or delivery pages like this one.

Scalability & throughput handling

As your business grows, the email API you use will have to adapt to your growing needs and handle different email-sending volumes without compromising the quality of the service.

And although not all services on this list provide good scalability, you can send large amounts of emails with all of them.

IP pools & email streams

A solid IP infrastructure consists of features such as dedicated IPs, manual or auto warm-up, IP pool management, etc. 

I’ll also look into separate sending streams, which go a long way when it comes to deliverability since they allow you to send transactional and marketing emails on separate IPs. 

Now, some API providers offer dedicated infrastructures through IP pooling or email queuing, but a true separate stream is what you need if you’re a high-volume email sender. That is, if you don’t want your emails to hit spam filters or damage your sender reputation.

Pricing comparison

An email API should be affordable, but at the same time, not cut back on important features like email logs or dedicated IP addresses. It should offer value for money and also let you choose a pricing plan according to the size of your business. For now, check out what you can expect from each provider’s pricing plans:

Ease of integration

Most providers nowadays support simple mail transfer protocol (SMTP), allowing you to send emails via relay mechanisms over RESTful API endpoints. To help you integrate the API with your project, they also offer SDKs, toolkits that contain everything from installation instructions to pre-built components and resources.

So, for research purposes of this article, I’ll dive head first into the documentation, GitHub repositories, and SDKs of every email service I review. I’ll check which programming languages they’re compatible with, the usage examples they offer, and more!

I’ll also look for quality-of-life features, which aren’t necessary at all, but can make your developer team’s lives easier. A great example is MCP servers, such as Mailtrap MCP and Postmark MCP. You can hook these up to your IDE or preferred AI helper, then send transactional emails or smoothen out your workflow.

Webhooks

With webhooks, you can get instant notifications when your emails get delivered or land in spam, when someone unsubscribes, etc. You can monitor your engagement, debug workflows, you name it.

Since all email API providers on this list offer webhooks, I’ll compare them by the types of events they support and their retry logic. 

Email analytics

Detailed analytics on email performance, such as open rates, bounce rates, and click-through rates, go a long way in improving your deliverability.

This is especially true since all major inbox providers nowadays have their own regulations, including:

• Google
• Yahoo
• Outlook
• Apple Mail

To comply with these, you need to be able to track your emails. For instance, Google requires you to stay under 0.1% spam rate if you don’t want to get blocked.

However, it’s important to make a distinction in the analytics email API providers offer. Some provide dedicated solutions like Mailtrap, while others, like Amazon SES, require integration with other services such as CloudWatch.

Security & compliance

Security 

Every email API should place strong emphasis on encrypting data, requiring authentication, and similar security measures. 

For the purposes of this article, I’ve researched how each provider handles encryption, API keys, how granular their user access is, if they support TLS and STARTTLS protocols, etc.

P.S. Over at Mailtrap, we’ve recently conducted in-depth research on email security for the top providers in the industry. Check it out! 

Compliance

Not complying with regulations like GDPR (EU) or CCPA (US), CAN-SPAM Act, and others can lead to considerable fines. For instance, not complying with the CAN-SPAM Act, you can get fined up to $44k per email.

So, to see whether an email API provider helps you comply with all the regulations, I’ve dug through pages like this one or this one.

Since the Mailtrap team leaves no stone unturned, we’ve also compared the compliance of the top providers. You can read it here.

Onboarding, UX & support

HTML previews, blacklist checks, email logs, webhook responses in JSON format, and templates are only some of the features every email API should offer to cater to diverse use cases and enhance user experience.

Additionally, verifying your domain shouldn’t be a headache, and a blocker shouldn’t take forever to deal with. That’s why I’ve checked what sort of customer support the API providers from this list offer and whether:

• Their team is available around the clock or not
• You get help if you’re migrating from another provider
• They provide email deliverability consultations

Customer experience

I’ll make sure to provide you with user testimonials for each platform I’ve found across the various social media platforms.

And I’ll also dig out the ratings from popular review websites such as G2 or Capterra.

Wrapping up

And we’ve made it!

I hope you enjoyed going through the haystack of email infrastructure services and best email APIs with me and that I’ve made your decision on which one to use a bit easier.

And as if you haven’t had enough of tables throughout this article, here’s another one that sums up the best email APIs for you:

Frequently asked questions

What is the best email API?

Since every team has its specific goals, needs, and wants, there really is no best email API. However, Mailtrap Email API is quite flexible and lets you control your sending process and fine-tune it according to your requirements. 

Which email API offers the best deliverability rates?

Based on the deliverability tests we’ve recently performed, Mailtrap and Postmark have the best deliverability rates. Using free plans, shared IPs, and identical email template, we’ve managed to achieve 78.8% deliverability rate with Mailtrap, whereas Postmark reached 83.3%.

How do I choose the best email API for my application?

When choosing the best email API for your application, first take into consideration your team’s requirements and goals. Then, take into account an API’s email infrastructure, ease of integration, webhooks, email analytics, security & compliance, and, of course, customer support and pricing.

If you need help choosing an email API, refer to our guide on choosing an email service provider.