I just had this problem so I thought I'd share my solution.
If you don't get any mails even though you have $email = true;
in your error.php you might have the same problem I had, i.e. e-mails were sent to webmaster @ www.domain.tld, instead of webmaster @ domain.tld.
The solution is to either directly enter the e-mail address like this:
$notify = 'email@example.com';
or, to let php remove the leading 'www.' part of the name, like this: