Validation

Hello,

Unfortunately Mailgun’s validation service doesn’t check if an email exists.

You can use the following alternative.

Create a file inside wp-content/mu-plugins (create this directory if it doesn’t exist) and place the following code:

<?php

add_filter( 'is_email', 'block_spammer_email' );

function block_spammer_email( $email ) {
    if ( 'ojaisexau@gmailzdfsdfds.com' == $email ) {
        return false;
    }

    return $email;
}

Also if you include a simple JavaScript on the comment form most of the spambots will fail.

https://github.com/jesinwp/wp-blockspam-js

This simple plugin adds JS code to the comment form which is completely transparent to your visitors. This will block 90% of spammers.