you could hand code a check for the email address filed:
<?php
if(isset($_POST['email'])) {
$emailArray = explode("@", strtolower($_POST['email']));
if(is_array($emailArray)) {
if(in_array("yahoo.com", $emailArray) || in_array("gmail.com", $emailArray)) {
header("Location: pageName.php?badDomain=true");
}
}
}
?>
this will redirect to page called pageName.php with a badDomainURL variable
pageName.php?badDomain=true"
use an if statement to show an error message if the bad domain uRL = true:
<?php if(isset($_GET['badDomain']) && $_GET['badDomain'] == "true" ) { ?>nope<?php } ?>
you can of course edit the page name in the code.