*** Problem Description ***
Mail in Exchange 2003 will backup in queues bound for other internal Exchange
servers, and then queue will go into a retry state. The error listed on the queues
will be Semaphore timeout period has expired.

The application log may register the following event:

Event Type: Warning
Event Source: MSExchangeTransport
Event Category: Connection Manager
Event ID: 4006
Date: 2/25/2004
Time: 1:33:58 PM
User: N/A
Computer: Server Name
Description: The connection was dropped by the remote host 10.1.1.1,
mail.domain.com; the semaphore timeout period has expired.




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There are several causes for this error. The following is a list of the most
common:

1. Symantec/Norton Corporate 9 Internet Email Auto Protect is running on any of the
Exchange Servers in that are involved. This is a feature of Norton 9 that scans
Internet Email. From Symantec document 2004052415562048, this feature should never
be run on any SMTP based Email servers, as it will cause mail flow problems. To
resolve this have the customer remove this feature from Norton using document
2004062410173948 from Symantec's Web site.

2. STNEF is a new feature of Exchange 2003. Unfortunately this feature is not
compatible with all email systems, and can cause mail flow to backup on the
Exchange 2003 server. In many cases it will report “Semaphore timeout period has
expired" as the cause for the retry in these cases. To resolve this behavior,
enable the registry key listed in article 254089.

3. Symantec Mail Security Heuristics Scanning. Symantec Mail Security (I think 4.5)
has a heuristics scan that will alter the messages causing the terminating period
to appear on the same line as the end of the message text. This will prevent the
message from terminating. Disabling this scanning will allow mail to flow
correctly

4. A corrupt Metabase can cause this behavior. If this is the case follow the steps
listed in article 304166 to replace the Metabase.

5. Remote server does not respond with any SMTP banner. This error can appear if we
connect to a remote SMTP server and it never returns a banner. Telneting to the
remote server will show if this is the case.

6. On some Cisco Firewalls In the firewall feature set, the statement IP INSPECT
NAME (site) SMTP is incompatible with ESMTP. Disabling this feature should resolve
the issue

There may be many other causes for this error. If you experience any please email
me with the details and I will update this article to include the cause and resolution.