Mailgun Email Validator


Most email validators look for an @ and a .(dot) some go further and blacklist certain domain names. But Mailgun’s Advanced email validation service goes deeper and looks for the existence of the domain name, presence of a MX record and the custom ESP(Email Service Provider) grammar.
The grammar here is the rules defined by each email provider. For example, Yahoo Mail addresses can only contain letters, numbers, underscores, and one period.
So perfectly passes the is_email() function but can never exist as it contains more than one period. Such addresses can’t escape Mailgun’s Email validation.

Why use Mailgun’s email validation service?

  • Performs the usual email syntax check.
  • Checks the existence of the email domain. So can’t escape.
  • Checks if the email domain has a MX record. So is caught.
  • Checks if the username complies with the grammar of its ESP (Email Service provider). Eg Gmail doesn’t allow usernames less than 6 characters and hyphens so and can’t get away.

Why use this plugin?

  • Integrates with the is_email() function of WordPress. So it works seamlessly with Contact Form 7, Jetpack/Grunion contact forms, WordPress registration form and any form which uses the is_email() function.
  • Kicks spam before it is inserted into the database
  • Ensures that the commenting process is uninterrupted even if Mailgun suffers a downtime
  • Works completely transparent, nothing changes in the frontend

This plugin requires a Mailgun Public API Key which can be obtained through a free sign-up at Mailgun(No credit card required).

If you’re trying out this plugin on a local WAMP/LAMP/MAMP installation make sure your system is connected to the Internet for this plugin to contact Mailgun.

Available Languages

Further Reading

Read about Mailgun’s email validation service.


  • Enter your public API key to begin validation.
  • A comment with an incorrect email address.
  • This plugin in action on the user registration page.
  • Email validation in a contact form.


  1. Unzip and upload the mailgun-email-validator folder to the /wp-content/plugins/ directory.
  2. Activate the Mailgun Email Validator plugin through the ‘Plugins’ menu in WordPress.
  3. Configure the plugin by going to General > Email Validation page.
  4. Signup for a Mailgun account (it is completely free no credit card required).
  5. Login, copy and paste your public API key to General > Email Validation page.


Why did you create this plugin?

I hate comment spam because it bloats my database. I also don’t like bugging my visitors with CAPTCHAs in the form of scribbled text,
counting the puppies and answering questions like What is 3 + 2?
So when Mailgun released their email validation service I tried validating the email addresses of comments in the spam queue of my blog.
I found that nearly 50% of these email addresses were identified incorrect by Mailgun.
Thus this plugin was born. Though not as effective as CAPTCHAs this plugin can prevent a decent amount of spam while maintaining user experience.

Is this plugin a product of Mailgun?

No. It only makes use of Mailgun’s email validation service API. Nothing in the code belongs to Mailgun.

I get a *401 Unauthorized* error when I verify the API key but I’m very sure that it is correct

You could be using the normal API key, for this plugin you need to enter the Public API Key this is slightly
longer than the normal API key and is found just below it.

This plugin is active and I have entered a Valid Public API Key but it doesn’t work

Try the email validation demo from the plugin’s option page. It could a connectivity issue.

What happens if Mailgun’s service is down?

In such cases emails are passed on untouched (as though this plugin is nonexistent) and on the front-end users won’t notice anything.

What contact form plugins are supported?

Any form which uses the is_email() function are supported this means the most popular ones like Contact Form 7, Jetpack by, Grunion Contact Form
and a lot of others are supported.

Does Mailgun support this plugin?

No, because Mailgun didn’t create it. If you need support create a thread
by choosing the Support tab of this plugin. If you directly create a thread in the forum I’ll never know of its existence.

I want to see a demo of emails validating

Mailgun has created a jquery demo at this page. The code for this demo is available here.


Hard to get started…

I needed a quick fix, so signed up, installed the plugin. Now the work starts: Then I am asked for email verification and registration…. bla,bla, done that.. THEN I get another popup: Enter your Phone Number… bla,bla.. for TXT verification.. sorry, this is TOO TIGHT, whats wrong just going through my email?
Also, If you enter a domain on their account panel, it will ask you to … go to the registrar… enter DNS records etc… another job I don’t wanna do, got enough on my plate

Shoot it down

Went for trial and was locked out before could even use. After a simple mailbox check to verify existence, if not restrict form completion. Usually, if you start off with issues, the rest follows, so abandoned as locking out users and requesting contact support before you start is a joke. Never put a bad or good comment on WordPress yet, but this deserves one and one star rating as well.

Read all 23 reviews

Contributors & Developers

“Mailgun Email Validator” is open source software. The following people have contributed to this plugin.




  • 16th October 2016
  • Removed PHP4 style constructors for PHP 7 compatibility



  • 19th October 2014
  • Use HTTP HEAD instead of GET to validate API key. More details…



  • 3rd November 2013
  • Plugin is translation ready


  • 5th October 2013
  • Initial version