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ban email domains

Ban email domains and usernames in Voxel



In this tutorial, I will show you how to enhance the registration process in the Voxel WordPress theme by blocking specific email domains(as given by Voxel in the latest update) and usernames. This can be a valuable addition to your website’s security and user management. I’ll guide you through the process of adding this functionality to your child theme’s function file.

Step 1: Prepare Your Child Theme

Before making any changes, make sure you have a child theme set up. This will ensure that your customizations won’t be lost when you update the Voxel theme. If you don’t have a child theme, you can create one using the official WordPress guide or just copy the provided one by Voxel.

Step 2: Open Your Child Theme’s Function File

In your child theme’s directory, locate the functions.php file and open it for editing. If the file doesn’t exist, create it.

Step 3: Add the Custom Filter

Inside your functions.php file, add the following code:

add_filter( 'voxel/registration-errors', function( $errors, $username, $email, $role ) {
    if ( ! is_email( $email ) ) {
        return $errors;

    $email_domain = substr( $email, strrpos( $email, '@' ) + 1 );
    $block_domains = [
        // Add more domains to block here

    // Check for blocked email domains
    foreach ( $block_domains as $domain_partial ) {
        if ( stripos( $email_domain, $domain_partial ) !== false ) {
            $errors->add( 'email_error', 'Blocked domain.' );

    // Check for blocked usernames
    $blocked_usernames = [
        'admin', // Add other usernames to block here

    if ( in_array( $username, $blocked_usernames ) ) {
        $errors->add( 'username_error', 'Blocked username.' );

    return $errors;
}, 10, 4 );

This code adds a filter to the registration process, checking for blocked email domains and usernames.

Step 4: Customize the Blocking Rules

You can customize the list of blocked email domains and usernames by editing the $block_domains and $blocked_usernames arrays in the code. Add or remove domains and usernames as needed.

Step 5: Save and Test

Save your functions.php file, and now your enhanced registration process is ready. Test it by attempting to register with blocked usernames or email domains. Users should receive appropriate error messages.

Here is an example list of disposable email providers you could ban:

Pros of Avoiding Third-Party Plugins:

  1. No Plugin Overhead: Many WordPress plugins, while useful, can introduce extra code and features that you may not need. By implementing custom features like this, you keep your site lightweight and efficient.
  2. Customization: You have complete control over the blocking rules. You can easily adjust the list of blocked email domains and usernames as your website’s requirements change.
  3. Security: Blocking specific usernames and email domains can enhance the security of your website by preventing potentially harmful or spammy registrations.
  4. Performance: Reducing the number of active plugins can contribute to better performance and faster load times for your website.
  5. Compatibility: Since you’re working directly with your theme, you can ensure that the customizations are compatible with the current theme version.

In this tutorial, I’ve shown you how to enhance the registration process in the Voxel WordPress theme by blocking specific usernames and email domains. This can help you maintain a more secure and spam-“free” user base while avoiding the need for third-party plugins. Remember to keep your child theme up to date and periodically review your blocking rules for any necessary adjustments.

If you do not have Voxel yet, you can support me by getting it through this link: Get Voxel

And check out my other Voxel related blog posts!

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