If you are missing an email that was already purged from your “Deleted Items” folder, it is possible to still recover it if it is within 14 days. The process below can be used to recover these types of messages.
Recovering Deleted Items from Office 365 Mail
Login to 365.mylmc.org
Look for the Deleted Items folder that is listed under your name, right click on Deleted Items, and choose Recover Deleted Items. A new window will pop up, so make sure that your pop-up blocker is disabled for this page.
Check the items that you would like to retrieve and click on the Recover option in the lower right corner of the screen or just right-click the email you need and choose Recover.