emails received by recipient and also sent to quarantine

mara2021 1,076 Reputation points
2024-05-24T03:11:20.73+00:00

Normally our quarantine for exchange online may have 2 or 3 items for review. Today there were quite a bit in the quarantine. Most for about 3 shared mailboxes. Some items had dates from 2 days ago. The quarantine is checked every day. I released the emails. We found out that the emails had been delivered previously and the users wanted to know why they appeared in the inbox again. We have Zix for our spam filter. How do I fix this? Something has changed. Thank you.

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  1. Noah Ma-MSFT 2,085 Reputation points Microsoft Vendor
    2024-05-24T09:23:08.7866667+00:00

    Hi @mara2021 ,

    Thank you for posting to Microsoft Community.

    Based on your description, I want to check with you if you mean there are some mails went to the user mailbox meanwhile it appeared in quarantine. If yes, it most likely something made the email be split into two copies.

    Could you please try the followings?

    1. Please kindly turn off the Zix filter to see if it makes a difference.
    2. Also, could you offer your Quarantine policies with me to check if it has an effect on the issue.
    3. Please run a message trace for the delivered emails. It will show what actions were taken on the message before it reached its final status. You could refer to the steps of Message trace in the new EAC in Exchange Online | Microsoft Learn.

    Hope it helps and looking forward to your update.