Hi Guys,
As per the below link which is closed, i have discovered the same thing happening with Build: 9.0.1~svn20110627r29113release9.0-1lenny on a more regular basis.
Specifically I had tracked it down to WebGuard Devices returning the 500 syntax error, command unrecognized reply but now there are more that don't use them.
http://forums.untangle.com/virus-blo...tax-error.html
For some reason the Kaspersky Virus Blocker is corrupting the DATA segment of the SMTP session. I can create a Policy to bypass the Default Rack that doesn't contain the Kaspersky Virus Blocker but ideally this shouldn't have to be the case right?
Any ideas?