Mail server sending mail but not receiving

Hi, From what I can tell I have the server all set up properly. DNS is resolving and reverse DNS is working great as well. Everything should be a go but no matter what I do I can't seem to receive any email on the OS X server. Here is the returned undeliverable message that kicks back to me when I try to send an email. Any help is much appreciated. If you need any more info from my setup please just ask I will be most grateful for any help. Thanks and take care ----- The following addresses had permanent fatal errors ----- (reason: 554 : Relay access denied) ----- Transcript of session follows ----- ... while talking to mail.pressnetexpress.com.: DATA : Relay access denied 554 5.0.0 Service unavailable : Relay access denied Last-Attempt-Date: Thu, 14 Sep 2006 13:42:09 -0700 (PDT)