Forminator - disallow use of specific e-mails, block submission

forminator-disallow-e0mails.php

<?php 

/************************************
*
* Forminator - disallow some e-mails, issue error
*
* by adamcz/WPMU DEV
* Tested with Forminator 1.15.14
*
* Use as MU plugin
*
* Adjust fields' IDs if needed to match your form
*
*********************************/

add_filter( 'forminator_custom_form_submit_errors', 'check_form_data', 99, 3 );
function check_form_data( $submit_errors, $form_id, $field_data_array ) {
	
	
	$mail_forms = array( 1445 ); // IDs of forms to check; if more than one, separate by comma 
	$mail_field = 'email-1';
	
	$error_msg = 'Invalid e-mail address!';
	
	// set disallowed e-mail adresses (may be partial only)
	$disallowed = array(
		'@gmail.com',
		'@yahoo.com'
	);
	

	if ( in_array( $form_id, $mail_forms ) ) {
		
		$email = '';

		foreach( $field_data_array as $arr ) {
	
			if ( $arr['name'] == $mail_field ) $email = $arr['value'];
			
		}
		
		
		foreach ( $disallowed as $to_check) {
			
			if ( stristr( $email, $to_check) ) $submit_errors[][$mail_field] = $error_msg;
			
		}
	
	}

	return $submit_errors;
}