When sending an email, an error was reported in the email tracking query: 550 "Sender" is invalid

Question

Use the Java code in Microsoft AP user: sendMail， An error occurred while sending. Before the error occurred, everything was normal when using this, but after a few days, the error appeared Another phenomenon is that this error only occurs when Azure invites users, but it does not occur when using administrator accounts.

Microsoft returned an error message to the email, and the following is the content of the response。

We haven't added or used this' qqqqq 'address, so we don't know why this email address appears

Answer 1

Hi Erik John,

Thanks for reaching out to Microsoft!

550 "Sender" is invalid error can occur due to several reasons, including an invalid or non-existent recipient email address, or if email is mistakenly identified as spam by the recipient’s mail server.

550 "Sender" is invalid is a response from the recipient’s mail server that signifies a failure in email delivery.

I would recommend you raise a support case, a Support Engineer will be able to look into this issue and assist you better. You can raise support ticket from New support request - Microsoft Entra admin center or https://admin.microsoft.com/#/support/requests.

Hope this helps.

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