We have an ASA5550 running 7.2 code and we have had to turn off the inspect esmtp to get all mail to pass. At first, I thought maybe an extended command that wasn't supported was the problem, but this is the synopsis from our server guy:
The SMTP problem was not a command level problem. It appears that the firewall was rejecting the SMTP session mid-transaction. At times I would see our server issue a 354 (ok, send the body) response to the client and then I wouldn't see anything further from the client. Sometimes I would see the beginnings of a message (after our server issued a 354) before the packet stream stopped coming to the mail server. The client would get a pop-up message saying that "The connection to the mail server has been interrupted". I fielded six trouble tickets that had this problem that were all resolved after the fixup-smtp was removed.
At this point the config has just statics and a basic ACL allowing DNS to those servers. I'm looking for some direction, we have the inspection turned off, but I want to turn it on as soon as possible. Thanks for all your help.
