Have an external user who is trying to email my domain on an exchange 2007 server and not mail filtering except for what exchange provides. The bounce back the external recieves is: Subject: Mail delivery failed: returning message to sender This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: The mail server could not deliver mail to . The account or domain may not exist, they may be blacklisted, or missing the proper dns entries. I've added the external users aliase to the custom filters exceptions and still being blocked. How can i allow this domain or one aliase to email into my exchange server?

Does it Exchange accept mail directly from the internet? It doesnt sound like it. That NDR doesnt sound like something Exchange woudl generate.

Hi, Any updates? What's your mail flow? Fireware->Edge->Hub? Seems like only this external user cannot send mails to your domain(more than one recipient)? It's better to copy full NDR here(please also hide some domain information). "I've added the external users aliase to the custom filters exceptions and still being blocked" Do you mean you use Set-ContentFilterConfig -BypassedSenders ? Try to add the external user as a Mail Contact or safe sender(Outlook) and test again. Frank Wang