Mail Security - Transport Agent bounces as Invalid Content

Hi, I have an installation on Exchange Server 2003, running Mail Security 4.3.10025.0
The customer complained that genuine email messages were getting bounced. I have traced this to Transport Agent (turning OFF solves the issue).
The error message is : host said: 554 5.6.0
Invalid content (in reply to end of DATA command)

The email message I have been experimenting with appears a fairly normal message, but has two MS Word attachments ( .doc ).
I assume it's not safe to leave Transport Agent OFF, so have checked it on again.
Does anyone have any idea whether I can tweak the Mail Security, or any other solution ? Thanks.

Note that I received the same message ok from the same sender, using Pop email, not through the Exchange Server with Mail Security. I then saved the two MS Word documents, and sent a new message to the recipient with the Word documents attached - that message successfully was delivered (with Transport Agent enabled).
Which suggests that the problem lies in the original message, not necessarily in the attachments.

 

Try the steps in the following KB Article to see if that resolves the issue at all. The article addresses slow mail service rather than not receiving at all but if the load produced by scanning the message causes the service to time out, that might be the issue. Let us know if this doesn't help at all.

Sending and receiving email is slow on my Microsoft Exchange Server with ESET Mail Security for Microsoft Exchange Server

 

Hi Dwomack, many thanks for your response. Eset support UK logged onto the server and have confirmed that it is a blacklisted URL in the body of the original message which kicked this out.
Seems the sender's IP is on one blacklist, although clear on many others.
It's just the combination of blacklists that caused this one bounce.
At the end of the day, Mail Security did what it says it does which is protect against reported spam or other problems. Endpoint Security uses a different anti-spam engine, which allowed the message through to my PC.
I'm very happy that Eset support are on the ball so quickly and thoroughly. Special thanks to you and Nick in UK Support.