Office 365 has a filter that will quarantine emails that may potentially be junk and/or flagged as dangerous. Users will be alerted by receiving an email message regarding any quarantined messages. There are three options to select in the email message; Block Sender, Release and Review. The user would select the appropriate option. 

NOTE: If users want the message to show in the Inbox, they would select Release.

See example below: 

If you prefer to check your quarantined messages online, you can use the direct link:

Users can search for messages by using the Sort results by filters. Click the drop down box and selecting the desired filter. 

NOTE: If no messages are quarantined, users will see No data available.