The following tutorial steps through the process of how to recover deleted items such as emails, contacts, tasks or events in Exchange Online using the Office 365 Outlook Web App. Please keep in mind the retention policies that apply to deleted mail:
Deleted Items folder:
Items remain in the Deleted Items folder for 30 days before being automatically removed.
Items removed from the Deleted Items folder:
Items that have been automatically removed from the Deleted Items folder are retained for 30 days before being permanently deleted.
On the left hand of the page in folder view, select the Deleted Items folder.
*Note: You may need to expand your mailbox's folder view to display the full contents. Learn more in the View Folders tutorial.
If the item you'd like to recover has been recently removed from the Deleted Items folder, right click the Deleted Items folder in the menu and choose Recover deleted items. You may also click on the message at the top of the pane reading Retrieve messages that were recently deleted or emptied from this folder.