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Tuesday, November 29, 2022

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
Specialized in Microsoft Azure - Office 365 / Microsoft Exchange; conducted numerous projects worldwide in designing, supporting, and implementing messaging and virtualization infrastructure for medium-sized and large enterprises. Further, I am a Cloud Architect and Technical Advisor for various start-ups.

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