microsoft / microsoft/MHA

Unknown fields DIR:INB;

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@stephenegriffin is already working on this.

Since Mar 18, 2025.

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Description

Both https://mha.azurewebsites.net/ and the Outlook add-in report DIR:INB as an unknown field. I believe this is in error since DIR: is well documented and INB means Inbound.

See https://learn.microsoft.com/en-us/defender-office-365/message-headers-eop-mdo

Repro steps:

  • Send an email from outside Office 365 to an Exchange Online mailbox. Use MHA to analize the headers and observe 'Unknown fields | DIR:INB;' in the output.

Expected behavior:

  • Analyze DIR: and eplain the meaning of INB, OUT or INT

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