Here is the issue that I have been facing for some time now. We are running an Exchange Server 5.5 on our system with service pack 4. We have been having trouble sending mails to 1, and only 1 ISP. We host our domain on our server. The ISP that we are having difficulty with is a part of AT&T. When we send messages to the ISP it returns:
c=US;a= ;p=XXX, Inc.;o=XXX?XXX;dda:SMTP=test@XXXXXXXX.XXX; on 7/24/2001 12:51 PM
Unable to deliver the message due to a communications failure
The MTS-ID of the original message is: c=US;a= ;p=XXX, Inc.;l=XXX_XXXX-010724164937Z-1279
As you can see there is no NDR code with this bounced message. Everyone in the company that tries to send there has this issue. Using NSLOOKUP toolfrom the ISP to our server, the mx record is perfect. All the .dll files have been updated correctly. What is being missed, and is there any solutions??
Thank You
