Sent Email Rejected with "Bad Sender" error


Under certain conditions Office365 will refuse to send emails, issuing a bounce reply that looks similar to this message:


As the email explains, the most common cause is that your account has been sending out too many emails in a short period of time. Unless you have been sending a very large volume of email to hundreds of recipients at a time, it is more likely your account has been compromised.


To resolve this issue:

  1. Immediately change your password using the Password Manager. This is essential to preventing further abuse of your account. 
  2. Forward or paste a copy of your bounce message to the helpdesk via email or a Self Service ticket. So long as we can verify your password was changed, the temporary ban imposed by Microsoft can be lifted.
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Article ID: 452
Wed 8/16/17 2:29 PM
Wed 11/8/23 2:51 PM