If you believe you are missing emails, they could have ended up in Office 365’s quarantine. Microsoft marks certain email senders as potentially fraudulent and quarantines their emails, effectively withholding them from a user’s inbox. Microsoft has increased its efforts to mitigate spam and phishing threats, and this has resulted in a larger number of false positives.

Quarantined email can be viewed in the Office 365 Security & Compliance Center.

1. Go to https://security.microsoft.com/quarantine
2. Login (if necessary)
3. The Quarantine window should already be displayed (a list of quarantined emails will be displayed if they are present). For reference the quarantine listing is found under “Email & Collaboration” and then under “Review”
4. Click any message to select it, then choose from the options given:
   • Release message
   • Delete Message
   • Preview message
5. If you are confident that the message was quarantined in error and contains no threats, you can release it to appear back in your inbox as normal
6. When releasing, in the popout pane that appears, choose whether to Report messages to Microsoft for analysis. This reports the erroneously quarantined message to Microsoft as a false positive. Please note that future messages from the sender may still be quarantined.