Answered Question
Jun 1st, 2010

I have an unusual problem where ESMTP is working to some but not other Message Labs servers.

I see this error on the ASA - ESMTP Classification: Dropped connection for ESMTP Request from inside:

Questions is - do I need ESMTP inspect on the firewall?

I have lowered the settings to "low" security for now too see if this helps.


I have this problem too.
0 votes
Correct Answer by Jennifer Halim about 6 years 4 months ago

Yes, pls go ahead and turn it off.

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Overall Rating: 5 (1 ratings)
Jennifer Halim Tue, 06/01/2010 - 03:39

Here is exactly what "inpsect esmtp" does for your information:

Basically in a nutshell, "inspect esmtp" restricts the smtp protocol to only the 15 SMTP commands, providing a more strict inspection on that protocol.

However, since all the mails will be inspected by MessageLabs, it should already been taken care off as Message Labs is solely providing email security.

Hope that answers your question.

rasoftware Tue, 06/01/2010 - 03:42

Yes - so this can be turned off?  All mail flows to and from Message Labs without external access.

I recall a few year back have to disable it on a PIX as it stopped Exchange servers talking to others correctly across the a VPN.


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