Junk mail filter

[Mgiordano]

We are having a problem where emails that were once marked safe and have been going to our inbox suddenly end up back in Junk Mail. We go back to the email and mark it safe again and it moves it to the inbox. It seems like after Office365 it gets declassified and sent back to Junk. How can I fix it so that once we mark it as safe it continues to go to our inbox?

Thanks

[#2]

This sound like the ZAP feature. Read more about it, how to identify messages affected by it and how to disable it if needed here: https://docs.microsoft.com/en-us/office365/securitycompliance/zero-hour-auto-purge