Check Quarantined Messages
If you are noticing that some emails are not getting to you even though they were sent, they may be quarantined. Microsoft does this to protect you from possible phishing and malware, however, they sometimes quarantine incorrectly.
To check and mark a message safe:
1. Go to https://protection.office.com/#/quarantine.
(Also under Threat Management > Review > Quarantine if it brings you to the Security and Compliance home page)
2. Sign in, using your Office 365 user ID and password.
3. On your Quarantine page, you'll see a list of any messages that were sent to you, but were identified as phishing/spam and redirected to the quarantine.
4. Sort or search messages as needed.
5. Double-click a specific quarantined message to view details about it, and take actions.
a. Click Preview message to see what is in the message.
b. If the message wasn't actually spam, you can release it (have it sent to your mailbox) and report it as not junk to the Microsoft Spam Analysis Team. To do so, click Release message and then make sure Report messages to Microsoft for analysis is checked and Release messages to all recipients is checked. Click Release messages again. The message should show up in your inbox shortly and you will get a pop up saying the message was successfully released.
6. You can also select one or more messages, and then choose an action from the Actions drop-down list (release or delete in bulk).
