When you delete a received email or a sent item, it goes into your Deleted
Items folder and can be retrieved from there.
If you've already emptied the contents of the Deleted Item folder, if you
are in an Exchange environment (often businesses use Exchange for their email
server) and the administrator has turned on Deleted Item Retention, then you
can retrieve even those deleted items for whatever length of time is
specified (ask your administrator how many days you have).
In your Deleted Items folder, click on Tools and "Recover Deleted Items"
(this is greyed out if you don't have that option). If you don't have the
option of recovering deleted items, there are third party applications that
you can purchase.
Someone else may have a better answer for you.
NOTE: that when you do go through the steps to recover a deleted item, it is
returned to your Deleted Items folder.
