Exchange: SMTP Connector to Smart Hosts Stops Responding

Summary

SMTP connector to Smart Host stops responding periodically after several days. Deleting the SMTP connector and re-creating corrects the issue and mail flow is resumed immediately. Reboot also resumes mail flow.

Resolution:

In this instance, the SMTP connector was configured to send mail to a Unix Smart Host. There was a communication issue in which the Exchange server thinks the Front End Smart Host is an Exchange server and tries to exchange link state information with it. To correct this issue, suppress sending link state information to the Unix Smart Host. Although link state information is exchanged between routing groups and thus only sent over Routing Group Connectors, in this instance, the Exchange server was treating the Unix smarthost as another Exchange server.


1) open REGEDIT on the Bridge Head server

2) Navigate to SYSTEM\CurrentControlSet\Services\RESVC\Parameters
3) Right Click on Parameters and select New, DWORD Value

4) Type in "SuppressStateChanges" without the quotation marks

5) Right Click on the new SuppressStateChanges dword value and select MODIFY

6) Set the Value Data to 1

For more information on Suppressing Link State Information, refer to documentation:

http://www.microsoft.com/technet/prodtechnol/exchange
/guides/E2k3TransnRouting/d4c84ac1-5ff9-4b6c-a2d7-80044c96e5e3.mspx?mfr=true


James Chong (MVP)
MCITP | EMA; MCSE | M+, S+
Security+, Project+, ITIL
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