Filter Disposable Email Addresses

The WS Form wsf_action_email_email_validate filter can be used to analyze and reject unwanted email addresses from form submissions.

The Filter

The wsf_action_email_email_validate filter is supplied with four parameters:

• $valid – True by default. Return this value in your function if the email validates.
• $email – The email address being validated.
• $form_id – The form ID the email address belongs to.
• $field_id – The field ID the email address was entered into (This will be false for emails checked in actions).

Your filter hook function can return one of the following return values

• True – The email address is valid, no action will be taken by WS Form.
• False – WS Form will show a standard error message indicating the email address is invalid.
• String – WS Form will show the string you provide to indicate the email address is invalid.

Sample Code

This code would typically be added to your themes functions.php file, preferably in a child theme.

// Add filter for disposable email addresses
add_filter( 'wsf_action_email_email_validate', 'wsf_action_email_email_validate_disposable_domains', 10, 4 );

// Hook function for wsf_action_email_email_validate filter
function wsf_action_email_email_validate_disposable_domains( $valid, $email, $form_id, $field_id ) {

    if( filter_var( $email, FILTER_VALIDATE_EMAIL ) ) {

        // Split email address by @
        $email_array = explode( '@', $email );

        // Extract domain
        $domain = array_pop( $email_array );
 
        // Check if domain exists in list of disposable domains
        if( in_array( $domain, wsf_disposable_domains() ) ) {

            // Return an invalid feedback message to be shown on the field
            return __( 'The email address provided cannot be used' );
        }
    }

    return $valid;
}

// Array of disposable domains
function wsf_disposable_domains() {

    return array(

        '0-180.com',
        '0-30-24.com',
        '0-420.com',
        '0-900.com',
        '0-aa.com',
        '0-mail.com',
        '0-z.xyz'

        // Add other domains here ...
    );
}