When you are using an IMAP e-mail account, you can restore messages that have been marked for deletion. Deleted messages are displayed in strikethrough text.
Select the deleted message.
On the Edit menu, click Undelete.
To quickly see all your messages that are marked for deletion, on the View menu, point to Current View and then click Group messages marked for deletion.
Note: When you purge the deleted messages, they no longer appear in Microsoft Outlook. They are deleted from the IMAP mail server and cannot be restored. Purging messages is similar to emptying the Recycle Bin on your Microsoft Windows desktop.