Greetings,
Ever since upgrading to Exchange 03, some users have issues sending or replying to emails from some domains. A NDR gets generated in one of two forms:
“The following recipient(s) could not be reached:
‘dave@somewhere.com’ on 2/1/2005 9:57 AM
There was a SMTP communication problem with the recipient’s email server. Please contact your system administrator.
or
“The following recipient(s) could not be reached:
‘Schmuck, Joe’ on 1/17/2005 9:35 AM
You do not have permission to send to this recipient. For assistance, contact your system administrator.
We use an external spam filtering service (an added line to our MX record directs all traffic through their servers first; our server only accepts connections from their servers- this to stop any potential relaying from client machines inside the network, if someone managed to get infected with something) and I thought that might be an issue, but it only occurs with a handful of domains. I’ve contacted the admins at those domains, and they state that they aren’t even seeing our traffic, and apparently, it’s my server that’s generating the refusal…
Any thoughts?