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The mail traffic is unable to pass through the ASA firewall, and the "%ASA-6-302014: Teardown TCP connection **** for outside: xxxx to inside:xxxx duration X:X:X bytes xxxx Flow closed by inspection" error message appears

Core issue

This issue occurs when the Simple Mail Transfer Protocol (SMTP) inspection is enabled in the firewall.

When this issue occurs, the %ASA-6-302014: Teardown TCP connection **** for outside: xxxx to inside:xxxx duration X:X:X bytes xxxx Flow closed by inspection error message appears.

This issue appears due to the presence of Cisco bug ID CSCsh33982.

The main cause of this issue is that a body packet drops from an SMTP communication, and the client retransmits until it stops.

In the syslogs, there is a teardown due to the inspection.

Resolution

For a temporary workaround:

Use the no inspect esmtp command in order to disable the SMTP inspection.

In order completely resolve the issue:

Upgrade to the  ASA version 7.2(2.12) or later.  In order to download latest software, refer to Cisco Downloads.

Version history
Revision #:
1 of 1
Last update:
‎06-18-2009 03:59 PM
Updated by:
 
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