problem mailing attachement

I'm using the coding at:

http://www.codewalkers.com/c/a/Email-Code/PHP-Text-HTML-Email-with-Unlimited-Attachments/

to send emails. However for some reason I can't send .exe files.. :S

I've tried
$msg->Attach("infobulletin.exe","");
$msg->Attach("infobulletin.exe","text/plain");
$msg->Attach("infobulletin.exe","application/octet-stream");

In each case I get the message that the email has been sended, but it never arrives at the person requesting the application

Can someone help me out on this?

I've never heard of attaching an exe. But you can attach a zip.

well it seems I've got the same problem when it's zipped :(
(user doesn't receive the mail)