none
SMTP Error 421 Service not available Exchange 2013 with CAS NLB

    Question

  • i have an application configured to relay email through exchange 2013 CAS on a custom relay connector. Application successfully send email whole day but with some missed entries show error code 421 service not available in orcale based application log.

    what could be the issue.

    Br,

    AA

    Tuesday, April 2, 2019 11:48 AM

All replies

  • A misconfigured connector could be the issue.  But we have no idea because you didn't tell us anything about what you configured. 

    NLB could also be the issue. You could rule that out by pointing the traffic to one of the servers, bypassing NLB.


    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!



    Tuesday, April 2, 2019 4:18 PM
    Moderator
  • Hi AA,

    How was the custom relay connector configured? What if we try with a new custom relay connector?

    >>but with some missed entries show error code 421 service not available

    Is there any more detail logged in the application log? Is there any thing in common among these missed entries?

    Do you have any AV/Firewall installed? Is it possible that the AV/Firewall was causing the issue?

    Regards,
    Steve Fan


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.


    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Wednesday, April 3, 2019 2:26 AM
    Moderator
  • Dear Ajnabi,

    Just wanted to say hi and check if there is anything that we can do for you on this problem. If so, please do not hesitate to let us know and we will be happy to help.

    Best regards,
    Steve Fan


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.


    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Friday, April 5, 2019 9:12 AM
    Moderator