In reading the Documentation, I understand that when smtp packets are inbound to the PIX, and fixup smtp is enabled, the non 7 commands are translated into XXX's. And it looks like the mailserver then recieved the XXX commands and replies with a 500 command not recognized.
What is not clear in my reading is does the PIX also look at smtp streams that are outbound as well and perform the same set of translations?
We are running 6.1.4 right now if the behavior of the PIX has changed from 6.1.4 to 6.3.x
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
[toc:faq]Introduction:This document describes details on how NAT-T
works.Background:ESP encrypts all critical information, encapsulating
the entire inner TCP/UDP datagram within an ESP header. ESP is an IP
protocol in the same sense that TCP and UDP are I...