SBS 2003 Exchange with SP2 no other rollups after that.
Server is upto date except some .net crap that won't install.
Email sent from outside LAN will sometimes bounce back to the sender with 5.2.1 error.
We have removed all limits on email sizes
It's not consistant at all, some will bounce some won't, we can't find a trigger that causes a message to bounce. Sometimes a message that's 17K will bounce from the server with a return to sender of 5.2.1
There does not appear to be anything touching the traffic like Anti Spam software or odd firewall software on the server.
Just plain old Anti Virus installed.
A telnet email session (25) with the server always results in a sucessfull email. With no 5.2.1 ever returned in my manual session with the server.
This has been going on for a few weeks, and I can not figure this out!
I have done extensive searching on this site and others.
Because it's across multiple users, I ruled out a currupt single user box.
Below is a transcript of a returned to sender message.
From: System Administrator
Sent: Wednesday, September 07, 2011 11:48 AM
To: ***********, J*****
Subject: Undeliverable: FW: DMV proposal
Your message did not reach some or all of the intended recipients.
Subject: FW: DMV proposal
Sent: 9/7/2011 11:44 AM
The following recipient(s) cannot be reached:
Ge**** ********** on 9/7/2011 11:48 AM
The message reached the recipient's e-mail system, but delivery was refused. Attempt to resend the message. If it still fails, contact your system administrator.