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554 5.0.0 Service unavailable RRS feed

  • Question

  • Hi All

    one of my user when sending email to one external user is getting the below NDR, not sure on this. please advise me on this

    The following addresses had permanent fatal errors ----- <extuser@extdomain.com>
        (reason: 554 5.4.14 Hop count exceeded - possible mail loop ATTR87[XY1ABC01UY016.xyz-NIP02.prod.protection.outlook.com])

       ----- Transcript of session follows ----- ... while talking to extdomain-com.mail.protection.outlook.com.:
    >>> DATA
    <<< 554 5.4.14 Hop count exceeded - possible mail loop ATTR87[XY1ABC01UY016.xyz-NIP02.prod.protection.outlook.com]
    554 5.0.0 Service unavailable

    Friday, July 3, 2020 2:44 PM

Answers

  • Hi,

    Do you have on-premises Exchange servers in your organization?

    Does this issue only occur with one user? Can he send messages to other external users with the same domain?

    Can other user send messages to this external recipient? You can post the screenshot of the NDR here, and don't forget to cover your personal information.

    Please do not use auto complete, try to enter the email address manually, and check if the issue can be reproduced.

    Here is a blog about this issue, you can check for more suggestions: Fix email delivery issues for error code 5.4.6 or 5.4.14 in Exchange Online.

    Regards,

    Lydia Zhou


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

    Monday, July 6, 2020 3:17 AM

All replies

  • Hi,

    Do you have on-premises Exchange servers in your organization?

    Does this issue only occur with one user? Can he send messages to other external users with the same domain?

    Can other user send messages to this external recipient? You can post the screenshot of the NDR here, and don't forget to cover your personal information.

    Please do not use auto complete, try to enter the email address manually, and check if the issue can be reproduced.

    Here is a blog about this issue, you can check for more suggestions: Fix email delivery issues for error code 5.4.6 or 5.4.14 in Exchange Online.

    Regards,

    Lydia Zhou


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

    Monday, July 6, 2020 3:17 AM
  • Just checking in to see if above information was helpful. If you have any questions or need further help on this issue, please feel free to post back.

    Regards, 

    Lydia Zhou


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

    Thursday, July 9, 2020 8:03 AM