Unknown fields DIR:INB;

[JetzeMellema]

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