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Dynamics 365 Community / Forums / Small and medium business | Business Central, N... / SMTP mail system relay...
Small and medium business | Business Central, N...
Suggested Answer

SMTP mail system relay of mail is not allowed

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Posted on by Manuel Araica 5

Hi Everyone, we just started experiencing this email issue.  No updates or changes has been done to the environment.

The SMTP mail system returned the following error: "Mailbox name not allowed.  The server response was: sorry, relay of mail is not allowed. (#5.7.1)

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  • Suggested answer
    Suresh Kulla Profile Picture
    Suresh Kulla 50,243 Super User 2025 Season 2 on at

    Are you using office 365? this error is coming from SMTP you need to check your SMTP setting or SMTP server if you have hosted locally.

  • Manuel Araica Profile Picture
    Manuel Araica 5 on at

    We are on office 365 and we will look into the logs.  No changes or smtp settings were made to the servers, so most likely the culprit can be outside the Nav environment

  • Suggested answer
    Marco Mels Profile Picture
    Marco Mels on at

    Hello,

    How are you executing the tests to get to this error? You can also simulate the error (or not) outside Dynamics NAV via Send-MailMessage PowerShell command let.

    Thanks.

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