One of the really bad email habits that I see people adopt is using their Deleted Items folder as an archive. The belief would seem to be that it is an ‘easy’ way to archive because it only takes a single keystroke (i.e. the Delete button) to ‘archive’ the email.
Because most on premise mail servers never enforced a retention policy (i.e. how long emails are kept) people were not penalized for their bad habits. However, in the world of Office 365 things are a little different. Let me illustrate this with an example.
After a user recently moved to Office 365 they were shocked to find that their ‘email filing system’ (i.e. their Deleted Items folder) had been emptied. Where was it? Why had it been emptied? How do you get it back? Panic! etc , etc, etc.
The reason those emails were removed is that by default Office 365 has a number of default email retention policies in place. One of these is that:
By default, in Exchange Online, the retention period for deleted items is 14 days. The retention period starts when the item deleted is moved to the Recoverable Items folder. After 14 days, items in the Deletions subfolder are automatically moved to the Purges subfolder.
Thus, 14 days after migrating to Office 365 the deleted items folder will be emptied by default. Then 14 days after that the deletions are then sent to purges where they remain for another 14 days. After that they are permanently removed from Exchange Online, i.e. bye, bye filing system. The best way to understand all this is look at:
Can the default retention policy be changed? Yes, but probably an easier way is simply NOT to use Deleted Items as an email archive. Create another folder and drag and drop the ‘email filing system’ there to ensure it is always retained! Deleted Items is designed for exactly what it is called! Deleted Items!
You can read more on Office 365 retention policies and tags here: