• Authenticate new users that sign up for your app/project [jump ahead]
  • Best for: eCommerce stores, SaaS, etc.
• Verify users that submit your contact form [jump ahead]
  • Best for: Simple contact forms

Disclaimer: Every line code in this article has been prepared by a developer and thoroughly tested before publication. It works with Python 3.7 and above.

Setting up Flask

Before working on your Flask app, I strongly recommend creating and activating a virtual environment, an industry-standard practice that isolates the required dependencies and prevents conflicts.

To create a virtual environment, use the following command:

python -m venv venv

And to activate it, use:

# Windows
venv\Scripts\activate

# Mac/Linux
source venv/bin/activate

Then, regardless of whether you go for user authentication or contact form verification, you will need the following:

• Flask 3.1.0 or above – The core web framework. 
• Flask-SQLAlchemy – Flask extension that adds support for SQLAlchemy.
• Python-dotenv – reads key-value pairs from a .env file and can set them as environment variables.
• ItsDangerous – For safely passing data and signing verification tokens.
• Flask-Mail – A Flask extension that lets us send emails with just a few lines of code.
• An SMTP service – Personally, I’ll be using Mailtrap SMTP throughout the article since it reliably sends emails for me, even on the generous free plan.
• A database – Needed to store user details and verification statuses. You can use:
  • SQLite – Built-in, suitable for smaller projects.
  • PostgreSQL or MySQL – Recommended for production
  • SQLAlchemy – What I personally use, since I find it an efficient way to manage the database (e.g., user data handling). Plus, it works with databases, prevents SQL injection, and provides an ORM (Object-Relational Mapping).
• Flash messages flash – For displaying success/error messages in Flask.
• URL routing url_for– To handle verification links.
• A frontend (Jinja2 templates) – To display signup forms, verification messages, and success/error pages.

Email verification in Flask

Email verification essentially checks whether there’s a real person behind a user address by sending them an email with a link they need to click on.

Typically, people submit their user’s email addresses when:

• Registering for websites or apps – User authentication
• Submitting contact forms – Contact form verification

So, choose your flow based on whether you have a project/app or a contact form. 🙂 

User authentication

The project structure we’re aiming for looks something like this:

Now, let’s get down to some coding!

1. Set up config.py

The config.py file contains app settings, such as Flask secret key, database configuration, and other email settings:

import os #  for loading SMTP credentials from environment variables
from dotenv import load_dotenv

# Load environment variables (optional)
load_dotenv()

# Flask App Configuration
SECRET_KEY = os.getenv("SECRET_KEY", "your_default_secret_key")

# Flask-Mail Configuration
MAIL_SERVER = os.getenv("MAIL_SERVER", "smtp.example.com")
MAIL_PORT = int(os.getenv("MAIL_PORT", 587))
MAIL_USE_TLS = True  # Use TLS for most SMTP providers
MAIL_USE_SSL = False  # Use SSL only if required (never enable both)
MAIL_USERNAME = os.getenv("MAIL_USERNAME", "your_email@example.com")
MAIL_PASSWORD = os.getenv("MAIL_PASSWORD", "your_email_password")
MAIL_DEFAULT_SENDER = "no-reply@your_domain"

# SQLAlchemy Database Configuration
SQLALCHEMY_DATABASE_URI = "sqlite:///database.db"
SQLALCHEMY_TRACK_MODIFICATIONS = False

Notes: Don’t forget to replace the placeholders with your actual SMTP credentials.

Additionally, if you’re using MAIL_USE_TLS = True, which is necessary for secure email sending, you shouldn’t set MAIL_USE_SSL, since only one should be enabled at a time. Additionally, MAIL_USE_SSL should be used only if your SMTP provider specifically requires it.

2. Define environment variables in .env file
Copy/paste the following code in your .env file and replace variables with actual Mailtrap credentials:

SECRET_KEY=your_default_secret_key
MAIL_SERVER=live.smtp.mailtrap.io
MAIL_PORT=587
MAIL_USERNAME=api
MAIL_PASSWORD=your_email_password

3. Define the user model in models.py

Next, we need to create a user model using SQLAlchemy, store email, hashed password, and verification status and set up database connection. All of this happens in the user model in models.py, which we need to define:

from flask_sqlalchemy import SQLAlchemy
from werkzeug.security import generate_password_hash, check_password_hash

db = SQLAlchemy()

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(100), unique=True, nullable=False)
    password = db.Column(db.String(255), nullable=False)  # Store hashed passwords
    verified = db.Column(db.Boolean, default=False)  # Email verification status

    def set_password(self, password):
        self.password = generate_password_hash(password)

    def check_password(self, password):
        return check_password_hash(self.password, password)

4. Mail initialization in mail.py

The mail.py file is responsible for initializing the mail object which we will later use to perform email sending in Flask:

from flask_mail import Mail

mail = Mail()

5. Token & email handling in email_utils.py

The email_utils.py file is responsible for handling verification token generation and validation, as well as sending the actual verification emails.

Here, we’ll use itsdangerous to generate secure tokens, implement a function to verify tokens, and set up an email-sending logic using Flask-Mail:

import logging
import traceback
from flask_mail import Message
from itsdangerous import URLSafeTimedSerializer, SignatureExpired, BadSignature
from config import SECRET_KEY
from mail import mail


# Set up logging configuration
logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s")

# Token Serializer
s = URLSafeTimedSerializer(SECRET_KEY)

def generate_token(email):
    """Generate a time-limited token for email verification."""
    return s.dumps(email, salt="email-confirm")

def confirm_token(token, expiration=3600):
    """Validate the token and extract the email if valid."""
    try:
        return s.loads(token, salt="email-confirm", max_age=expiration)
    except SignatureExpired:
        logging.warning("Verification token expired.")
        return False  # Token expired
    except BadSignature:
        logging.warning("Invalid verification token.")
        return False  # Token is invalid

def send_verification_email(to, verify_url):
    """Send the verification email with a secure link."""
    try:
        msg = Message(
            subject="Verify Your Account",
            recipients=[to],
            html=f"""
            <p>Click the link below to verify your email:</p>
            <p><a href="{verify_url}">{verify_url}</a></p>
            """
        )
        mail.send(msg)
        logging.info(f"Verification email sent to {to}.")
    except Exception as e:
        logging.error(f"Error sending email to {to}: {str(e)}")
        logging.error(traceback.format_exc())  # Logs full error traceback

6. Configure main app file (e.g., app.py)

Our main application file basically ties everything together, since it initializes Flask, SQLAlchemy, and Flask-Mail. It also creates signup and verification routes and handles user registration and email verification.

Here’s a code snippet example you can copy:

from flask import Flask, render_template, request, redirect, url_for, flash
from sqlalchemy import inspect
from models import db, User
from email_utils import generate_token, confirm_token, send_verification_email
from mail import mail


app = Flask(__name__)
app.config.from_pyfile("config.py")

# Initialize extensions
mail.init_app(app)
db.init_app(app)

# Create database tables if they do not exist
with app.app_context():
    inspector = inspect(db.engine)
    if "user" not in inspector.get_table_names():
        db.create_all()

@app.route("/signup", methods=["GET", "POST"])
def signup():
    if request.method == "POST":
        email = request.form["email"]
        password = request.form["password"]

        if User.query.filter_by(email=email).first():
            flash("Email already registered.", "danger")
            return redirect(url_for("signup"))

        new_user = User(email=email)
        new_user.set_password(password)  # Hash password
        db.session.add(new_user)
        db.session.commit()

        # Generate token & send email
        token = generate_token(email)
        verify_url = url_for("verify_email", token=token, _external=True)
        send_verification_email(email, verify_url)

        return "Please check your email for the verification link."

    return render_template("signup.html")

@app.route("/verify/<token>")
def verify_email(token): 
    email = confirm_token(token)
    if not email:
        return "Invalid or expired verification link."

    user = User.query.filter_by(email=email).first()
    if user and not user.verified:
        user.verified = True
        db.session.commit()
        return "Your account has been verified!"
    else:
        return "Account already verified."

if __name__ == "__main__":
    app.run(debug=True)

7. Create a signup form (e.g. templates/signup.html)

As you’re reading this article, I am pretty sure you already have a signup form, but just in case you don’t, here’s a basic template you can use:

<!DOCTYPE html>
<html>
<head>
    <title>Sign Up</title>
</head>
<body>
    <h2>Sign Up</h2>
    <form method="POST">
        <input type="email" name="email" placeholder="Enter email" required>
        <input type="password" name="password" placeholder="Enter password" required>
        <button type="submit">Sign Up</button>
    </form>
    {% with messages = get_flashed_messages(with_categories=True) %}
        {% if messages %}
            {% for category, message in messages %}
                <p class="{{ category }}">{{ message }}</p>
            {% endfor %}
        {% endif %}
    {% endwith %}
</body>
</html>

8. Create an email template (e.g., templates/verify_email.html)

Then, a little bit more frontend action because we need to create an HTML email template that will contain our verification link.

Here’s a basic one you can tweak according to your liking:

<!DOCTYPE html>
<html>
<head>
    <title>Email Verification</title>
</head>
<body>
    <p>Hi,</p>
    <p>Click the link below to verify your email address:</p>
    <p><a href="{{ verify_url }}">{{ verify_url }}</a></p>
    <p>If you did not sign up, you can ignore this email.</p>
</body>
</html>

9. Run the code and test the authentication logic

Execute the following command:

python app.py

Or, if you’re using Flask’s CLI:

export FLASK_APP=app.py  # Mac/Linux
set FLASK_APP=app.py      # Windows

flask run

Lastly, open http://127.0.0.1:5000/signup in your browser and create an account. Next, check your email for the verification link, click on it, and confirm the success message. For extra points, you can try logging in to verify the authentication flow. 

10. (optional) Debugging in case of errors 

To debug, check for missing dependencies with:

pip freeze

And that’s it, you have successfully implemented user authentication logic! 

If you wish to add additional layers of security to your web app or Flask contact form, consider adding email validation logic to your sign up form to protect yourself against spammers and bots.

Contact form verification

The project structure for contact form verification we’re aiming for looks something like this:

P.S. Our awesome YouTube team has prepared a short and sweet guide on email verification in Flask, so be sure to check it out! ⬇️

1. Set up config.py

The config.py is the heart of our email-sending configuration and contains the SMTP details Flask needs to send verification messages.

And here’s a code snippet you can copy/paste:

import os
from dotenv import load_dotenv

# Load environment variables (optional)
load_dotenv()

# Flask App Configuration
SECRET_KEY = os.getenv("SECRET_KEY", "your_default_secret_key")

# Flask-Mail Configuration
MAIL_SERVER = os.getenv("MAIL_SERVER", "smtp.example.com")
MAIL_PORT = int(os.getenv("MAIL_PORT", 587))
MAIL_USE_TLS = True  # Use TLS for most SMTP providers
MAIL_USE_SSL = False  # Use SSL only if required (never enable both)
MAIL_USERNAME = os.getenv("MAIL_USERNAME", "your_email@example.com")
MAIL_PASSWORD = os.getenv("MAIL_PASSWORD", "your_email_password")
MAIL_DEFAULT_SENDER = "no-reply@your_domain"

Note: Don’t forget to replace the SMTP placeholders with your own credentials (or define them in .env in the step below). You can even use Gmail for this, but due to its limitations, I recommend Mailtrap again. 🙂

2. Define environment variables

Create an .env file, paste the following code snippet, and insert your Mailtrap credentials:

SECRET_KEY=your_default_secret_key
MAIL_SERVER=live.smtp.mailtrap.io
MAIL_PORT=587
MAIL_USERNAME=api
MAIL_PASSWORD=your_email_password

3. Initialize the mail object

The mail.py file is responsible for initializing the mail object which we will later use to perform email sending in Flask:

from flask_mail import Mail

mail = Mail()

4. Set up email verification logic in email_utils.py

Next, let’s generate a secure token and add our sending logic along with the email content:

import logging
import traceback
import re
from flask_mail import Message
from itsdangerous import URLSafeTimedSerializer, SignatureExpired, BadSignature
from config import SECRET_KEY
from mail import mail

# Set up logging configuration
logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s")

# Token Serializer
s = URLSafeTimedSerializer(SECRET_KEY)

TOKEN_EXPIRATION_SECONDS = 900  # 15 minutes

def generate_token(email):
    """Generate a time-limited token for email verification."""
    return s.dumps(email, salt="email-confirm")

def confirm_token(token, expiration=TOKEN_EXPIRATION_SECONDS):
    """Validate the token and extract the email if valid."""
    try:
        return s.loads(token, salt="email-confirm", max_age=expiration)
    except SignatureExpired:
        logging.warning("Verification token expired. Ask the user to request a new verification email.")
        return False
    except BadSignature:
        logging.warning("Invalid verification token.")
        return False

def send_verification_email(to, verify_url):
    """Send the verification email with a secure link."""
    try:
        msg = Message(
            subject="Verify Your Email",
            recipients=[to],
            html=f"""
            <p>Click the link below to verify your email before your message is processed:</p>
            <p><a href="{verify_url}">{verify_url}</a></p>
            <p>If you did not submit this request, ignore this email.</p>
            """
        )
        mail.send(msg)
        logging.info(f"Verification email sent to {to}.")
    except Exception as e:
        logging.error(f"Failed to send email to {to}: {str(e)}")
        logging.error(f"Traceback for {to}:\n{traceback.format_exc()}")
        logging.warning("Possible causes: incorrect SMTP credentials, network issues, or email provider blocking.")

def is_valid_email(email):
    """Simple email validation function"""
    email_regex = r"^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$"
    return re.match(email_regex, email)

5. Configure main app file (e.g., app.py)

Our main app file, app.py, boots the Flask app, configures email handling, and sets up routes for both the contact form and verification.

And here’s the code snippet you can copy/paste:

from flask import Flask, render_template, request, redirect, url_for, flash
from email_utils import generate_token, confirm_token, send_verification_email, is_valid_email
from mail import mail

app = Flask(__name__)
app.config.from_pyfile("config.py")

# Initialize Flask-Mail
mail.init_app(app)


@app.route("/contact", methods=["GET", "POST"])
def contact():
    """Handles contact form submission and sends verification email."""
    if request.method == "POST":
        name = request.form["name"]
        email = request.form["email"]
        message = request.form["message"]

        if not name or not email or not message:
            flash("All fields are required!", "danger")
            return redirect(url_for("contact"))

        if not is_valid_email(email):
            flash("Invalid email format. Please enter a valid email.", "danger")
            return redirect(url_for("contact"))

        # Generate token and send verification email
        token = generate_token(email)
        verify_url = url_for("verify_email", token=token, _external=True)
        send_verification_email(email, verify_url)

        flash("A verification email has been sent. Please check your inbox.", "success")
        return redirect(url_for("contact"))

    return render_template("contact.html")

@app.route("/verify/<token>")
def verify_email(token):
    """Handles email verification after clicking the link."""
    email = confirm_token(token)
    if not email:
        flash("Invalid or expired verification link.", "danger")
        return redirect(url_for("contact"))

    flash("Your email has been verified. Your message has been submitted!", "success")
    return redirect(url_for("contact"))

if __name__ == "__main__":
    app.run(debug=True)

6. Create a contact form (e.g., templates/contact.html)

If you’re reading this, you probably have it, but just in case, here’s a simple code for a simple contact form:

<!DOCTYPE html>
<html>
<head>
    <title>Contact Us</title>
</head>
<body>
    <h2>Contact Us</h2>
    <form method="POST">
        <input type="text" name="name" placeholder="Your Name" required>
        <input type="email" name="email" placeholder="Your Email" required>
        <textarea name="message" placeholder="Your Message" required></textarea>
        <button type="submit">Submit</button>
    </form>
    {% with messages = get_flashed_messages(with_categories=True) %}
        {% if messages %}
            {% for category, message in messages %}
                <p class="{{ category }}">{{ message }}</p>
            {% endfor %}
        {% endif %}
    {% endwith %}
</body>
</html>

And if you want to check out how we do it at Mailtrap, be sure to check out the cool video we have on making a contact form in Flask:

7. Create email verification template (e.g., templates/verify_email.html)

For the user email that will hold the verification link, we’ll use the following template:

<!DOCTYPE html>
<html>
<head>
    <title>Email Verification</title>
</head>
<body>
    <p>Hi,</p>
    <p>Click the link below to verify your email before your message is processed:</p>
    <p><a href="{{ verify_url }}">{{ verify_url }}</a></p>
    <p>If you did not submit this request, ignore this email.</p>
</body>
</html>

8. Run the code and test the verification logic

Finally, let’s run the code with:

python app.py

Or, you can also set up Flask’s debug mode:

export FLASK_APP=app.py   # Mac/Linux
set FLASK_APP=app.py       # Windows

flask run

Lastly, open http://127.0.0.1:5000/contact in your browser, fill out the contact form, and once you hit submit, you should see a status update in your console/logs. Then, click the email verification link in the email and confirm the success message.

Wrapping up

That was quite a bit of code, wasn’t it? 😅

Fortunately, you can now verify users for both your web application and your contact forms in Flask, which should keep your email list spotless! 

Happy verification!

For that, you’ll need the help of email verification tools.  

I took it upon myself to give 11 of them a test drive and, with that, help you pick one from the many available options. 

So, if you’re looking for reviews and comparisons between some of the leading email verification solutions (which also double as email validation tools 🙌🏻), keep on reading!

The best email verification tools: a snapshot

As I know some of you might be looking to make a quick pick and start cleaning your email list ASAP, I’ll first provide you with a quick recap of how 6 of the best email verification tools stack up against each other.

Best accuracy

During my test drives of the 11 email verification tools covered in this article, I can safely say that all have near-perfect accuracy, so it’s hard to pick one as the “most accurate”. That being said, as you’ll see in the table below, as well as the tool’s website, NeverBounce promises the highest accuracy of 99.9%.

Best speed

If your email lists are quite large, a fast email verification tool is a must. And with an impressive verification speed of 0.012 seconds/email, Emailable significantly stands out among the tools I reviewed, making it the fastest of the bunch.

The largest number of integrations

Emailable not only beats the competition in terms of speed but in terms of the number of integrations as well, as it offers 90+ covering a range of email service providers (ESPs), customer relationship management solutions (CRMs), eCommerce platforms, and marketing platforms.

Most number of features

Plenty of features is what you’ll get with each tool on my list. Still, if you really want to get the most bang for your buck, then you should consider giving Hunter a go. The comprehensiveness of this tool is truly impressive and, for some, might justify Hunter’s pretty high price (spoiler alert). 

Biggest number of resources

The team behind a tool should equip you with different kinds of resources along with reliable customer support in case you need help, especially as a new user. I found that Bouncer handles this aspect the best by providing not one, not two, but four types of resources.

Most affordable

If you want to save money on email verification tools, the good news is that all the tools mentioned in this article, except NeverBounce, offer a free plan. So, if you want to test out a few solutions before making any financial commitment or use a tool long-term without any costs, then you have plenty of options to choose from. On the other hand, if you’re ready to invest in your email verification efforts by paying for extra features/credits, Clearout will provide you with the most budget-friendly option, whether you choose a pay-as-you-go plan or a monthly subscription. The runner-up in terms of affordability is ZeroBounce, with its monthly subscription.

For those seeking a fresh alternative, VerifiedEmail, a newer entrant to the market, offers one of the lowest pay-as-you-go starting points at just $7 per 1,000 emails, making it an attractive option for small teams and businesses that want enterprise-grade performance without overspending.

To make your own judgment of what email checker/verifier is best for you, I recommend taking a look at the table below for some more quick information, as well as reading my first-hand review of each tool.

Comparison criteria to keep in mind

For this round of reviews, I used 6 criteria to help me pick out email verification solutions worth giving a try. Let’s take a loot at each one now!

Accuracy 

To truly clean a list, an email verification tool should be able to accurately decipher between invalid email addresses, such as those with syntax errors/typos, spam traps, and so on. If the tool lacks in the accuracy department, that opens the door for bounces, deteriorated sender reputation, and lower deliverability for email campaigns.

Speed 

Along with removing the task of verifying emails manually from my hands, I want the tool of my choice to be able to get the job done quickly, regardless of email list size. This way, I can see results fast and get my email deliverability back in shape even faster.

Integrations

As email marketing tools, cold outreach tools, and other types of platforms are used by my team and me on a daily basis, the email verification tool we go for needs to have integrations with said platforms or at least support Zapier so we can create our own integrations. This way, we streamline our workflow and boost overall productivity.

Reporting 

Just as important as knowing that an email verification tool is doing its job is knowing what exactly the tool did after the email list cleaning is done. For that, I like to rely on reports and analytics provided by the tools, thus making them must-have features.

Pricing 

To make sure a tool doesn’t exceed my financial limits, I look for transparent and fair pricing. An added bonus is a free email verification tool trial or free credits/free plan. This way, I can get a sense of what using the tool is like before committing to any yearly or monthly subscriptions.

Solid and honest reviews 

While one email verification tool might be a gem in my book, in someone else’s, it might be a total failure. That is why, in order to make the reviews in this article a bit more objective, I also took into consideration the reviews left by other users and, with that, their experience using a specific tool. That being said, even when simply assessing whether an email verification tool is good, reliable, and, most importantly, right for me, plenty of positive and non-paid-for reviews from users are what I look for.

Now, onto my experience using 11 great email verification tools!

Bouncer

If simplicity is what you’re after, then Bouncer could be the tool for you. With it, verifying email lists of up to 250k email addresses will be a breeze as a drag-and-drop mechanism is at your disposal.

Overview: 

Along with the mentioned ease-of-use, Bouncer’s reliance on proprietary algorithms supported by Artificial Intelligence is what made me include it on this list. These algorithms negotiate with SMTP servers so you can get the most accurate results possible, which was certainly the case during my usage of the tool.

Rating:

• Capterra 4.8 (203 reviews)
• G2 4.8 (184 reviews)

Best for:

• Email marketing teams looking for user-friendly tools
• Small but fast-growing companies

Pros:

• Ease of use: The tool is notably user-friendly. Even as a first-time user, I found its interface intuitive and straightforward.
• Reliability and efficiency: Bouncer consistently showed me high reliability and efficiency in email verification. It seamlessly handled various lists, ensuring accurate results.

Cons:

• Perceived slowness in response: There were instances where the tool’s response time seemed longer than anticipated. While this might partly be attributed to my own expectations for speed, it’s an area where enhancements could potentially be made.

Pricing: Free version with limited credits available. Subscription plans start at $50/month, while pay-as-you-go plans start at $0.008 per email.

Support: Email, chat, and in-person support

NeverBounce

First on this list is a platform with a primary function to help you clean lists quickly and when necessary. With NeverBounce’s Clean feature, you can do a quick initial check and know in an instant whether you need to clean up your entire list or not, thus saving time and effort.

Overview:

Along with the Clean feature, NeverBounce also offers services to help you achieve pristine email list cleanliness. One such service is recognizing an excessive number of dubious email addresses and alerting the NeverBounce team to come in and do personal quality assurance. And while I haven’t tested this service out myself, its potential handiness is evident. 

Rating:

• Capterra 4.4 (41 reviews)
• G2 4.4 (136 reviews)

Best for:

• Nonprofits (they receive a 20% discount)
• Enterprises and startups wanting to adhere to strict email provider guidelines

Pros:

• Industry-leading detection capabilities: The tool excelled in detecting disposable emails and catch-all emails. Its efficiency in this area stood out to me as one of the best.
• User-friendly interface: I found the software very easy to navigate and understand. Its intuitive interface made the process of managing a list of emails straightforward, which actually came in handy for demonstrating the value of list cleaning to my superiors.

Cons:

• Challenges in CRM integration: When attempting to integrate the tool with our CRM system, I found the process quite challenging. The integration was not as seamless as expected, which posed a hurdle in efficiently streamlining the email verification process within our existing workflow.

Pricing: Pay-as-you-go plans start at $0.008 per email.

Support: Email, phone, and live chat support

VerifiedEmail

If speed and precision are your priorities, VerifiedEmail is a great choice. Built with a proprietary, on-demand infrastructure, it delivers real-time email verification for both individual addresses and bulk lists, ensuring campaigns hit the right inboxes.

Overview:

VerifiedEmail is a new tool on the market that, according to its creators, combines accuracy and affordability with enterprise-grade performance. It checks syntax, domain health, MX records, mailbox status, and even provides a score for each address to help you decide whether to send or skip. 

During our testing, the verification process proved to be fast and provided detailed and actionable results.

Rating:

• Capterra N/A (new)
• G2 N/A (new)

Best for:

• Marketing and sales teams running regular campaigns
• Agencies managing multiple client lists
• E-commerce brands that rely on signup forms and landing pages

Pros:

• High accuracy: Provides highly accurate and consistent results, even though it delivers in real time. 
• Scalable and cost-effective: Uses a pay-as-you-go model starting at just $7 for 1,000 emails, making it accessible for businesses of all sizes.
• Seamless integrations: Can be paired with HubSpot, Zapier, and other popular platforms.

Cons:

• Limited analytics: The platform doesn’t have any campaign reporting features or analytics.
• Learning curve for API setup: Depending on their experience, developers may need time to fully integrate API-based workflows.

Pricing: Free trial with 200 credits available. Pay-as-you-go plans start at $7 for 1,000 emails.

Support: Email support

Emailable

When doing email list verification on a regular or even semi-regular basis, chances are you won’t be uploading lists from the same source. For that reason, a tool such as Emailable comes in handy as it allows you to choose between uploading from a computer in CSV (.csv), Excel (.xlsx), or Text (.txt) format or connecting to an email marketing platform.

Overview:

Time efficiency is something you can expect to improve as an Emailable user, thanks to its bulk email verification and real-time verification features offered alongside single email verification. For me, the list-cleaning process using this tool usually took only a few minutes, after which I got to examine a detailed report generated by Emailable. 

To save even more time, I didn’t shy away from trying Emailable’s automated email verification directly inside my team’s database.

Rating:

• Capterra 4.8 (331 reviews)
• G2 4.8 (244 reviews)

Best for:

• Marketers looking to improve deliverability and email marketing campaign ROI
• Developers looking for an email verification tool with production-ready integrations

Pros:

• Flexible import options: The tool offers the convenience of directly importing email lists from a device or integrating with platforms like Mailchimp, making it very useful for marketers such as myself who deal with a range of different projects and have lists stored in multiple locations.
• Simple installation process: The installation process was straightforward and quick. I really appreciated the ease with which I could get the tool up and running without any technical hurdles.

Cons:

• Occasional missed hard bounces: I noticed that the tool sometimes missed flagging a few undeliverable emails. And while this only occurred with a small number of emails each time, it’s an area where the tool could improve.
• Complexity in understanding verification status: At times, I found it challenging to decipher the status of verified email addresses. The interface or the reporting system could be more intuitive to make this aspect clearer and more user-friendly.

Pricing: Free version with limited credits available. Subscription plans start at 25,50€/month, while pay-as-you-go plans start at 0,006€ per credit.

Support: Email and chat support

Clearout

The easy-to-use and well-known email verification tool, Clearout, is great at ensuring an accuracy of 98%+. The tool does over 20 comprehensive validation checks to verify email addresses. Along with that, it checks for greylisting, detects spam traps, verifies MX records, and does much more.

Overview:

Whether it’s a small number of email addresses or large lists, Clearout has both an instant email verifier and a bulk email verifier to check them. All you have to do is upload your email lists in .CSV or .XLSX format. Exporting files in .CSV format is also possible!

Besides its instant and bulk email verifiers, Clearout does have a Google Sheets add-on to quickly verify email addresses directly in your spreadsheets without having to juggle between lists or multiple uploads and downloads. 

Another cool feature I found in Clearout is its API for instant and bulk email validation. This allows for high flexibility as the API can be integrated into software written in a range of programming languages.

Rating:

• Capterra 4.7 (82 reviews)
• G2 4.7 (160 reviews)

Best for:

• Email marketers looking to clean their email list and improve email deliverability
• Sales/marketing professionals who do not want to ruin their domain sender reputation while doing outreach
• Lead generation companies who are looking for verified contact details of target B2B professionals

Pros:

• Seamless integration with HubSpot chat flows: Whether they come from customer support or an interactive marketing chatbot, Clearout ensures emails are validated right at the point of capture.
• More than just email verification: Clearout doesn’t just verify emails; it also has an email finder for quick and large-scale email searches. Additionally, it offers a LinkedIn prospecting Chrome extension along with in-app search, helping you extract pre-verified contact information from the LinkedIn platform.
• Quick resolve time: Clearout’s customer service team is always on their feet, ready to answer any questions you may need assistance with.

Cons:

• Doesn’t support campaign scheduling: Lacks support for sending, automating, and scheduling email campaigns right after cleaning a list.
• Limited CRM integrations: While Clearout integrates directly with almost all forms, most CRM integrations are done through Zapier or Make. A direct integration would have saved me time and effort.

Pricing: Free version with limited credits available. Subscription plans start at $31.5/month, while pay-as-you-go plans start at $0.007 per credit.

Support: Email and chat support

Hunter

Comprehensiveness is Hunter’s second name, as this email outreach platform is equipped with email address verification and email finder tools which will check an address on multiple levels – format, presence of MX records, usage of webmail such as Gmail or Yahoo, mail server response, and more. On top of that, it will also verify whether the email address is publicly visible on the web.

Overview:

If you really want to dig in deep with your email verification, then Hunter may well have all you’re looking for. 

Besides the email address verification status, this tool will also provide you with information on the sources and make a comparison with a unique database of professional email addresses.

Along with that, what I found especially convenient about this tool is that it comes in the form of a Google Sheets add-on facilitating email verification directly within the spreadsheet software.

Rating:

• Capterra 4.6 (602 reviews)
• G2 4.4 (518 reviews)

Best for:

• Sales representatives, recruiters, and marketers working for businesses of all sizes

Pros:

• Comprehensive and accurate database: Hunter stands out with its extensive and precise database, which, in my experience, consistently provided dependable results for both finding and verifying email addresses.
• Exceptional customer service: The Hunter customer service was prompt in their responses, often getting back within a couple of hours. They were helpful in addressing questions not covered in their FAQs, which themselves were quite comprehensive and informative.

Cons:

• Pricier than expected: The subscription plans are more expensive than I anticipated, which could be a concern for those with tighter budgets.
• Simplistic and glitchy interface: The user interface is rather basic and occasionally glitchy. A more sophisticated design with reliably functioning buttons would’ve significantly improved my experience.

Pricing: Free version with limited credits available. Subscription plans start at 34€/month.

Support: Email and chat support

Allegrow

For teams looking to move beyond simple SMTP “existence” checks, Allegrow positions itself as a modern deliverability platform focused on B2B sales and marketing teams. Its primary function is to solve the two biggest problems legacy verifiers can’t: identifying hidden threats (like spam traps and known spam reporters) and providing definitive “valid”/”invalid” statuses on catch-all contacts.

Source: https://www.allegrow.co/

Overview:

What made Allegrow stand out is its “signals-based” approach. Instead of just “pinging” a server, the platform analyzes over 30+ B2B-specific signals to verify each contact individually, not just at the server level. This allowed it to provide a definitive “Valid” or “Invalid” status even on the most challenging catch-all emails, which other tools tend to simply return as “unknown” or “accept-all”.

It’s also more than a one-time list cleaner. Allegrow is a full-suite deliverability platform that natively integrates into sales tools like Outreach, Salesloft, and HubSpot. Its “Safety Net” feature automatically verifies and blocks emails to high-risk contacts before every email gets sent, which is critical for protecting domain reputation. This, combined with daily spam rate monitoring and hourly authentication checks, makes it a comprehensive solution for GTM teams.

Rating:

• Capterra N/A
• G2 4.8 (60 reviews)

Best for:

• B2B Sales, Marketing, and RevOps teams.
• Companies relying heavily on email outbound with tools like Outreach, Hubspot or Salesloft.
• Data providers and high-volume agencies needing a scalable, high-accuracy API able to reliably handle millions of requests.

Pros:

• Definitive Catch-All Verification: This is its biggest advantage. It consistently gives a clear “Valid” or “Invalid” status on complex catch-all addresses, which unlocks a large portion of B2B contacts, given that catch-alls generally make up to 30% of servers within these email lists.
• Finds Hidden Threats: The tool is built to find “silent killers” like spam traps, manual spam reporters, low engagement traps, and dead emails that legacy tools are blind to, protecting sender reputation proactively.
• Full Deliverability Suite: Allegrow is not just a verifier. The native integrations, unlimited verification plan, and proactive domain monitoring are a complete package for managing an entire GTM team’s email deliverability.

Cons:

• B2B-Specific Focus: The platform’s signal-based analysis is heavily tuned for B2B contacts. Teams with purely B2C or consumer lists might not leverage their full capabilities.
• Higher Pricing Than a Simple Verifier: For a user who just wants to upload a single CSV for a one-time clean, the full suite of monitoring and integrations might be more than they need.
• Onboarding Recommended: To get the full value from the “Safety Net” integrations and monitoring, it generally requires a bit more setup than simpler drag-and-drop tools.

Pricing: Offers a 14-Day Free Trial to analyze up to 1,000 contacts. Paid plans include a “Starter” plan ($99/month) for individuals and a “Scale Plus Unlimited” plan ($1,340/month) for teams, which includes unlimited verification. A custom “API Plan” is available for high-volume power users.

Support: Dedicated Customer Success Manager (CSM), Live Chats, Group Video Sessions, email support, Comprehensive Help Center, and Technical Support team for API users.

ZeroBounce

“Military-grade security” is a bold statement, but it is also how ZeroBounce describes its email verification tool. So, if you’re a data security enthusiast, you should consider ZeroBounce as your tool of choice.

Overview:

ZeroBounce definitely passed my “accurate and easy-to-use email verificator” test. But what made this tool stand out, in particular, is the email deliverability toolkit it provides. This toolkit helps its users improve their email deliverability even further after cleaning their email list, which is not something you get with every email verification tool.

Rating:

• Capterra 4.8 (424 reviews)
• G2 4.6 (382 reviews)

Best for:

• From solo business owners to companies like Amazon, Disney, Netflix, and Sephora
• Anyone wanting a platform with email verification, deliverability, and email-finding features included 

Pros:

• Exceptional customer service: The customer service provided by the tool was noteworthy. I experienced quick and efficient feedback, which significantly contributed to a smooth user experience.
• Actionable intelligence from metadata: I was impressed with the detailed metadata provided by the tool. This feature offered great actionable intelligence, aiding in more informed decision-making.

Cons:

• Complex initial setup: I found that the initial setup process was somewhat challenging. The configuration and understanding of the tool’s features were not as straightforward as I had hoped, requiring additional time and effort to become proficient.

Pricing: Free version with limited credits available. Subscription plans start at $15/month, while pay-as-you-go plans start at $0,008 per credit.

Support: Email, chat, and phone support

Kickbox

Kickbox is an automated solution for email verification that offers a robust API you can easily integrate with the email tools you’re already using. Its focus is on providing a user-friendly experience, pure transparency, rigorous compliances, and an efficient verification tool.

Source: https://kickbox.com/

Kickbox is an automated solution for email verification that offers a robust API you can easily integrate with the email tools you’re already using. Its focus is on providing a user-friendly experience, pure transparency, rigorous compliances, and an efficient verification tool.

Overview:

As far as “accurate and easy-to-use email verifiers” go, Kickbox passed my tests with flying colors. Moreover, its dashboard provides comprehensive insights and a proprietary Sendex™ score, which helps improve email performance beyond simple list cleaning. My addresses were also validated instantly and I was able to correct typos on the spot, which is always a plus.

Rating:

• Capterra: 4.6 (68+ reviews)
• G2: 4.5 (160+ reviews)

Best for:

• Businesses of all sizes, from small startups to large enterprises
• Marketers seeking deep integration with tools like Mailchimp, HubSpot, and others

Pros:

• Advanced security and compliance: Kickbox adheres to the highest security standards, making it a safe choice for sensitive business communications.
• Comprehensive analytics: The platform’s detailed reporting and quality scores for each email address empower users with actionable insights to optimize their email strategies.
• Dedicated support: Kickbox offers personalized consulting, free webinars, and robust community resources, which I easily navigated through while testing the service.

Cons:

• Cost: While not the most budget-friendly option, Kickbox’s pricing reflects its premium features and reliability.
• Verification time: I found that larger lists required more time to process, which could be a consideration for users with time-sensitive verification needs.

Pricing: Free trial available with 100 credits to start. Pay-as-you-go pricing options start at $5 for 500 credits.

Support: Email, phone, and live chat support

GetProspect email verifier 

GetProspect is a lead generation platform that offers an email verifier with a 97%+ accuracy rate, which lets you instantly check the validity of your email addresses. 

Overview:

With the GetProspect email verifier, you can check up to 20 addresses without downloading them and instantly know which ones are valid and which shouldn’t be on your list.

For bigger email lists, GetProspect lets you efficiently perform bulk address verification by uploading them in CSV and XLSX formats. 

You can also verify your addresses without even leaving your Google Sheets or integrate the email verifier into your app thanks to GetProspect’s simple and understandable API.

Lastly, GetProspect has native connections to HubSpot, Pipedrive, Zoho, and various other CRM systems for easy connection and data transfer.

Rating:

• Capterra: 4.5 (91 reviews) 🌟
• G2: 4.0 (38 reviews) 🌟

Best for:

• Marketers who want to increase email delivery efficiency and improve ROI on email marketing strategies;
• Online companies that strive to constantly find new potential customers and expand their geographic presence by using convenient integrated solutions.

Pros:

• Straightforward interface – GetProspect has quite an intuitive interface, which you’ll get the hang of whether you’re tech-savvy or not.
• High data accuracy – Because of its 12-step email verification process, the GetProspect email verifier has super high accuracy on top of working in real-time.
• A wide range of functions – The service offers many valuable and effective solutions for quickly and profitably working with email and addresses of potential clients;

Cons:

• Possibility of false data – According to some users, the service sometimes provides false information or cannot determine the exact status of the address;
• Resettable counter – At the end of the month, the service usage counter is reset to zero, regardless of whether you use the paid or free version;

Pricing: 

• Starter subscription is $49/month with a 30% discount on annual subscription

Support: 

• Contact via email 
• Live chat support
• Comprehensive Help Center

Snov.io

If you’re looking for a versatile tool that does more than just email verification, Snov.io might be the perfect fit for you. Its 7-tier email verifier feature ensures that your email lists are always accurate and up-to-date, helping you reduce bounce rates and improve campaign performance.

Overview:

Snov.io’s email verifier checks email addresses from single inputs or bulk lists in real-time. Its powerful algorithms ensure that every contact is checked for syntax errors, domain issues, and mailbox existence. Also, Snov.io offers other instruments, such as email finder and drip campaigns, making it a one-stop platform for email outreach.

One of the standout features of Snov.io is its Chrome extension, which allows users to validate emails directly from LinkedIn, company websites, or search results. While I haven’t used this extension extensively, its ability to work alongside lead-generation activities seems promising.
Rating:

• Capterra: 4.5 (213 reviews)
• G2: 4.6 (400+ reviews)

Best for:

• Marketing and sales teams looking for an all-in-one outreach platform
• Startups aiming to streamline lead generation and email validation processes

Pros:

• Integrated workflow: The tool combines email finding, verifying, and automating follow-ups in one platform, simplifying the outreach process.
• Real-time validation: The ability to validate emails on the spot allows you  to create email lists quickly and easily.
• Affordable pricing for smaller teams: Its flexible pricing makes it accessible for startups and small businesses.

Cons:

• Limited standalone email verification features: While Snov.io’s verification tool is robust, it’s most effective when paired with its other features. Standalone users may find other platforms more specialized for email cleaning.
• Bulk verification is available only on paid plans.

Pricing: Free trial available. Paid plans starts at $39/month (1,000 credits)

Support: Email, call center, 24/7 live chat, and knowledge base

Email verification as part of email testing

Email testing is a complex process consisting of many “layers”, and depending on how detailed you want to be during this process, email verification might be a part of it.

You see, along with testing email content and design, running spam checks, checking email responsiveness as well as rendering, and doing other tasks necessary to ensure your email campaigns are effective, efficient, and deliver the intended user experience, diligent email marketers also clean the lists these campaigns will be sent to.

And while we have covered 11 great tools you can use to do said list cleaning, we have yet to touch upon a proper email testing solution.

A testing tool I use on a daily basis is the one offered by Mailtrap.

With Mailtrap Email Testing, you can inspect and debug emails in staging, dev, and QA environments before sending them to recipients. This way, if any errors are present in the email content or even the HTML/CSS code, you can spot and fix them, all while having no risk of spamming recipients with testing emails.

Some of the most notable features of this testing include:

• Spam score checking
• HTML/CSS checking
• Email previewing
• Blacklist reporting
• API for QA automation

So, if you are looking for a tool that solves multiple email testing challenges, Mailtrap Email Testing might be for you. But, if you are in need of something to help you get rid of email addresses causing high bounce rates and hurting your deliverability, then one of the email verification services reviewed earlier in the article is worth giving a try!

Run email verification your way!

Phew! What a long, information-packed journey this article has taken us on. Hopefully, it will be really useful for you when making your pick for the best email verification tool.

Remember, all the tools mentioned have great ratings backed by hundreds and even thousands of reviews. But, to make sure a tool will truly be what you need it to be and you don’t end up with a “bad email checker”, identify what your non-negotiables are and move from there.

So, say you want ease of use, then Bouncer won’t disappoint. Or maybe you need lots of flexibility when it comes to importing options? In that case, Emailable is a top candidate.

Hunter will provide you with a collection of features that will make any email marketer jealous. While ZeroBounce’s metadata will come in handy when making data-driven decisions.

Lastly, if you go for NeverBounce, you’ll be using a tool that is hard to beat in catch-all and disposable email detection. 

Some pretty solid options for email verification tools if you ask me!

Want more content on email verification or email testing? Check out some of our other articles:

• How to Handle Email Verification in Laravel
• How to Automate Email Verification in Selenium
• How to Test Emails in Different Clients 

However, that’s not all bad news. Developers and QAs also mean different things under validation and verification methods. 

First, let’s clarify this terminology confusion and then see how you could do both: validate and verify emails without actually sending an email.

What is email verification?

Email verification is a process that helps verify if there is an actual user on the receiving end of the email address. It consists of sending an activation link/code to an email address, which the end user should activate from their inbox.

The role of email verification is to:

• Increase your outreach
• Protect your sender’s reputation
• Prevent hard bounces and high bounce rates
• Prevent your email domain from being blacklisted
• Increase security and prevent users from malicious data input
• Keep your email-sending list up-to-date and free of bad emails
• Cut costs on email marketing (not to waste money on useless inactive or falsified email addresses and contact lists)

Note that email verification is often interchangeable with “email address verification.” This is another term that refers to ensuring that an email address is valid, properly formatted, and capable of receiving emails. Honestly, I don’t recommend using these two interchangeably for your clarity’s sake, or your own sanity, whichever you prefer.

Email verification vs email validation

As there are countless different explanations for email verification vs validation, I think it’s time we get to the bottom of this once and for all.

Put simply, verification is a more complex procedure than email validation as it involves both the frontend and the backend. 

Whereas, validation is only typically done at the frontend as it checks email format, detects and prevents typos (i.e. gamil.com instead of gmail.com)and invalid email addresses being entered into any of your forms.

For easier understanding, let’s imagine the two processes as mailmen. 📫

Email validation would be a mailman who, before he sets out, checks the address format on each letter, confirming street names and house numbers are correct. He also makes sure that certain addresses (like those for a university’s “edu” domain) accept specific deliveries.

Now, think of email verification as a mailman who not only checks the address format but also goes to each house to see if someone is there to receive the letter (what a mailman, right?).

Both validation and verification directly influence customer experience, as they ensure users receive timely, relevant messages without interruptions or errors.

Why must you verify emails?

One of the main reasons you must verify emails is because it’s likely that your emails may end up nowhere without verification. Moreover, verification boosts inbox placement and prevents issues such as email bounces.

The thing is that many hard bounces impair your sender’s reputation. The poor reputation, in turn, drops your deliverability, which, ultimately, decreases your opens, clicks, and conversions. If you regularly send emails to undeliverable addresses, your email campaigns will end up in the spam folder. 

Email marketing campaign performance depends on the accuracy of your email list, and, of course, your suppression lists.

On top of that, Google and Yahoo have released new deliverability updates for 2024, which consist of new rules for bulk email senders. 

The updates aim to increase email security, reduce spam, and improve overall user experience and email deliverability.

See the table for more information:

How to verify emails?

As previously mentioned, email verification includes both frontend and backend. Let’s go over the whole process so you can have a clearer picture.

Frontend implementation

• User input – Develop an interface on your website or application where the user can enter their email address. This is typically a part of registration or subscription forms.
• Basic validation – Implement client-side validation to check for the presence of the ‘@’ symbol, a domain, and the absence of invalid characters.

Backend implementation

• Generate activation code or link – Your backend system needs to generate a unique code or link whenever a user submits their email.
• Send email – Use an email sending service (e.g., SMTP email servers or third-party services like Mailtrap Email Sending) to send an email with the activation code or link to the user’s email address.
• Activation link or code – Once the user gets the verification email, they need to either follow the link or enter the code you provide them with on your website/app.
• Database update – After the user has verified their email address, their status is updated in the database.

In our dedicated Mailtrap tutorial, we cover the backend implementation of email verification using PHP:

Email verification tools

Among some marketers and communities, email validation tools are, as you can see, called “email verification tools.” They do the validation part in the email verification process.

Jenny, our expert on email infrastructure has tested a plethora of these email verification services, analyzed web feedback, and selected the top five tools based on the following criteria:

• Domain name / MX record check
• Single email verification
• Bulk email verification
• Syntax check
• Mail server validation
• Email verification API
• Disposable email address detection
• GDPR compliance
• Integrations
• Pricing
• Solid reviews

Here is the list of winners:

1. NeverBounce
2. Emailable
3. Hunter
4. Bouncer
5. ZeroBounce

But you should keep in mind that top-notch email verifiers are not free. You pay for and receive a set of techniques in a package, such as:

• Syntax verification
• Email address deduplication
• Spam trap identification and removal
• Bounce detection
• Toxic domain identification
• MTA validation

Lastly, if you’re looking for a free email checker to see whether a couple of newly added subscribers are using valid email addresses, you can simply make a free account at one of the platforms we listed above and use their free trials.

Email verification best practices

After consulting Yaroslav, our email deliverability specialist,I decided to list some of the best verification practices to help you keep your list of emails as clean as possible. Namely, you should:

• Integrate real-time API – You can integrate most of the tools I listed above into your workflow or website, which, through syntax check, SMTP and DNS check, ensures you gather accurate information whenever you get a new customer. API integration can be quite useful for demo request forms, free trial signups, gated content forms, and other registration pages. You should also check out Mailtrap email API, which ensures your messages will reach recipients’ inboxes in no time.
• Include security measures – To enhance the safety and integrity of your email verification process, and protect both your and the user’s data, you should implement measures such as expiration times for activations links. On top of that, you should use secure transmission protocols, like the ones I mentioned earlier.
• Provide clear messages and feedback – Provide clear messages and feedback throughout the process, so that users can complete it more easily and have a better experience.

Wrapping up

And we made it! 

I hope that this article will come in handy when you’re verifying your emails and choosing the best tools and methods.

But, improving your email verification game is only one way of achieving better email deliverability. Combine it with an effective email testing solution, and you’ll ensure your emails reach the intended recipients’ inboxes and keep them engaged too.

Mailtrap Email Testing provides me with a safe SMTP server environment that imitates a real server for testing emails, analyzes my emails against common spam filters, lets me spot and fix any errors in the HTML/CSS code if there are any, and more.

Now, in case you’re looking for more content to take your email verification and email testing knowledge to the next level, check out our video on verifying emails in Laravel: