If you believe that your IPS is preventing SMTP and POP3 sessions, you need to look at your logs to see what signatures are firing.
Reproduce the problem and at the CLI you can type "show event alert past 01:00" this will show the events for the last 1 hour. Once you find the signature(s) number that have an event action such as Drop, Reset or Shun you can disable those actions for that signature.
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...
Table of Contents 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 an...