I had a user complain that emails having been received so I checked the mail logs and I noticed that cox.net and bellsouth.net are rejecting mail from my server. Cox.net gives me this info from the error code But I used the DNS wizard and I have both A and MX records for the domain. I get a similar issue with bellsouth. I did a check and reverse DNS reports correctly. Not sure where to go with this. Any advice? edit ----- I did some more testing and sent a message from squirrel main on the server which went through fine. So, something is going on with the PHP mail headers.