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Outbound TLS authentication failed with error SubjectMismatch for Send connector Outbound to Office 365 RRS feed

  • Question

  • Hello team !!

     

     

     

    A costumer is having issues with cloud users in a Hybrid deployment  of Office 365.

     

    The MX record is pointing to an On-premises Exchange 2010 server. Cloud users cannot receive mails , local users are working fine

     

    In the  Exchange server event record we can see this message: Outbound TLS authentication failed with error SubjectMismatch for Send connector Outbound to Office 365. The TLS authentication mechanism is DomainValidation. Target is domain.mail.onmicrosoft.com.

     Any ideas would be greatly appreciated . thanks in advance

    Tuesday, August 28, 2018 1:24 PM

All replies

  • Hi Germain

    As per your description I would prefer to check if the certificate's subject name matches the domain name that you entered if you chose to use only a specific domain name for TLS verification.

    Kindly refer to the article given below :

    https://technet.microsoft.com/en-in/library/ms.exch.eac.connectorlearnmoreaboutvalidationtasks%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

    Thanks


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

    • Proposed as answer by Niko.Cheng Wednesday, August 29, 2018 8:39 AM
    Tuesday, August 28, 2018 9:42 PM
  • Hi germain,

    Robin is right, you need to check that your on-premises email server has Transport Layer Security (TLS) enabled, with a valid certification authority-signed (CA-signed) certificate, and the certificate subject name includes the domain name that matches the primary email server in your organization.


    Best Regards,
    Niko Cheng


    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.

    • Proposed as answer by Niko.Cheng Tuesday, September 4, 2018 2:23 AM
    Wednesday, August 29, 2018 8:41 AM
  • Hi ,

    I'm just writing to check how's everything going? If you have any questions or needed further help on this issue, please feel free to post back. If the issue has been resolved, please mark the helpful replies as answers, this will make answer searching in the forum easier and be beneficial to other community members as well. Thanks for your understanding.


    Best Regards,
    Niko Cheng


    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.

    Tuesday, September 4, 2018 2:23 AM
  • We had this issue after a change to networking/security systems on our network that were interfering with the connection.
    Thursday, April 9, 2020 5:25 AM