Try creating a blank page that sends an email with:
<?php
$to = 'nobody@example.com';
$subject = 'the subject';
$message = 'hello';
$headers = 'From: webmaster@example.com' . "\r\n" .
'Reply-To: webmaster@example.com' . "\r\n" .
'X-Mailer: PHP/' . phpversion();
mail($to, $subject, $message, $headers);
?>
If that doesn't send, then that implies it is an issue with your SMTP server and not the code. If that works, then I'd probably need FTP access and a url to look at the page and test it to see why it isn't working on your page.