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Monday, July 15, 2024

Disabling AuthGSSAPI on Receive Connector of Exchange Server

Submitting Messages on Port 587 from F5 SMTP Mailer failing with AUTH GSSAPI Remote(SocketError)

when i bypass F5 load balancer its submitting messages directly to the exchange server without any issues.


When i am submitting via F5 . I can see its initiating AUTH GSSAPI protocol from the listed supported protocols and fails to Submit the Message.

Default log location


2019-08-19T08:38:51.744Z,EXCH1\Client Frontend EXCH1,234255E01EE2EF03,2,,,<,EHLO F5DMZ, 2019-08-19T08:38:51.744Z,EXCH1\Client Frontend EXCH1,234255E01EE2EF03,3,,,>,250 EXCH1.azure365pro.com Hello [] SIZE 37748736 PIPELINING DSN ENHANCEDSTATUSCODES STARTTLS AUTH GSSAPI NTLM 8BITMIME BINARYMIME CHUNKING,
2019-08-19T08:38:51.746Z,EXCH1\Client Frontend EXCH1,234255E01EE2EF03,4,,,<,AUTH GSSAPI, 2019-08-19T08:38:51.747Z,EXCH1\Client Frontend EXCH1,234255E01EE2EF03,5,,,>,334 ,
2019-08-19T08:38:52.797Z,EXCH1\Client Frontend EXCH1,234255E01EE2EF03,6,,,-,,Remote(SocketError)

Disabled GSSAPI from Listed Available Protocols – Setting EnableAuthGSSAPI to $false

Set-ReceiveConnector "EXCH1\Client Frontend EXCH1" -EnableAuthGSSAPI $false

To Check 

Get-ReceiveConnector "EXCH1\Client Frontend EXCH1" | fl *binding*,*GSS*

Applied the same for all members in the pool of Exchange Servers

Once Disabled. It submitted the message without any issues.

To Revert Back –

Set-ReceiveConnector "EXCH1\Client Frontend EXCH1" -EnableAuthGSSAPI $true


Satheshwaran Manoharan
Satheshwaran Manoharanhttps://www.azure365pro.com
Award-winning Technology Leader with a wealth of experience running large teams and diversified industry exposure in cloud computing. From shipping lines to rolling stocks.In-depth expertise in driving cloud adoption strategies and modernizing systems to cloud native. Specialized in Microsoft Cloud, DevOps, and Microsoft 365 Stack and conducted numerous successful projects worldwide. Also, Acting as a Technical Advisor for various start-ups.

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