Blacklist emails in WordPress to Lead for Salesforce CRM v2.2+

block_non_biz_emails.php

<?php
add_filter('sfwp2l_validate_field','block_non_biz_emails', 10, 4);

function block_non_biz_emails( $error, $id, $val, $field ){
	
	if( $id == 'email' ){
	
		$non_biz_domains = array( 'gmail.com', 'yahoo.com', 'hotmail.com', 'aol.com' );

		$domain = array_pop(explode('@', $val));
		
		if( in_array( $domain, $non_biz_domains ) ){
			$error['valid'] = false;
			$error['message'] = 'Please enter a business email addresss.';
		}
		
	}
	
	return $error;
}