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Office 365 mailbox got compromised?

    Question

  • Hi, 

    We have a lot of users received emails coming from an Office 365 mailbox but the sender claims he never sent those emails. 

    It looks like his mailbox is somehow compromised. 

    What should we do?  

    Please advise.  

    Thanks. 
    Monday, February 13, 2017 9:06 PM

All replies

  • Hi, 

    We have a lot of users received emails coming from an Office 365 mailbox but the sender claims he never sent those emails. 

    It looks like his mailbox is somehow compromised. 

    What should we do?  

    Please advise.  

    Thanks. 

    1. ask him Change his password.

    2. Verify if the messages were really sent from his mailbox with message tracking. have you checked the sent items?

    If you don't access to do that, then create a rule to block the sender.


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    Monday, February 13, 2017 9:11 PM
  • Verify from the message headers that they're really coming from an Office 365 mailbox.

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    Tuesday, February 14, 2017 1:36 AM
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