Hi, I have a SBS 2003 server runing Exchange 2003. I can send email (to a particular company) and it gets delivered without issue. When that company replies, my client never gets the email. We did a trace and saw an exception error. class smtplib.smtprecipientsrefused: 550, all recipients refused. This seems to be only happening for a specific company email address. Thanks Lou

That doesnt sound like an Exchange error. Where are you seeing this error? How are you doing the trace?

The trace was actually sent to me from the company domain my server is denying emails from. We can send to them successfully but when they reply or send us a new mail, it never makes it to my client's inbox. The company sending the mails never get any rejection notices. They ran the trace and sent me information. I saw in the trace that my server was denying emails from them. Thanks Lou

Is there any SMTP gateway or firewall that inspects SMTP traffic between your Exchange Server and the Internet? Can they send you the actual SMTP logs or if you have them, post here?

Yes. We have a Cisco PIX 506E on our network between the Internet and our internal network. I will get the smtp trace info and post here soon.

Here is part of the actual trace. 20100426:11:42:09|14717916|9563|Exception occurred: Type=<error type> Exception=<exp> -|<class 'smtplib.SMTPRecipientsRefused'>:(550, 'All recipients refused')| I should clarify. My firewall security engineer setup the PIX so I'm not sure if its setup to monitor smtp traffic. This is an isolated issue with one client domain.

Ok, at the very minimum, ensure you have the ESMTP Fixup stuff disabled on the PIX: http://support.microsoft.com/kb/320027 Cannot send or receive e-mail messages behind a Cisco PIX firewall