Why Microsoft decided to keep deleted items in Exchange Online and why it might be the right decision

Some interesting discussion has flowed into my mailbox since Microsoft announced their decision to stop cleaning out the Deleted Items folder of user mailboxes in Office 365. The announcement appeared on February 20 and started a 28-day countdown to implementation. Just about now, deleted items are starting to accumulate in an Exchange Online mailbox near you.

Eight months on, I didn't like this decision when it was made and it still causes me concern, but I understand why Microsoft made it. In fact, this is a great example of a decision made for the majority that affects a sizeable minority. The majority is composed of the many small businesses that use Office 365, most of which care little about the wonders of compliance regimes. The minority comes from large enterprises, most of whom care very much about how email is stored and controlled.

But a support call from a small tenant costs Microsoft as much grief and expense as one that comes from a large enterprise. That's not strictly true because large enterprises are often assisted by a Technical Account Manager (TAM) who can escalate matters if required. But the point is that when you look at the volume of support calls attributed to a particular issue, you focus on the numbers and concentrate on how to reduce that call rate.

And as it turns out, lots of small tenants experience problems when they delete messages only to find that Exchange Online has removed those items sometime later. It seems that lots of people triage their Inbox by deleting items that are of no interest or they don't want to deal with immediately (the Clutter feature should be of great use here). Perhaps mobile clients with their "swipe to remove" gestures have contributed to this mode of working, but in any case, lots of items end up in the Deleted Items folder that users subsequently go looking for.

In the old regime, the Managed Folder Assistant cleans out the Deleted Items folder after items are 30 days old. Items can still be recovered in the next 14 days, but if someone deletes an item and goes looking for it 45 days later they run into unhappiness. Cue a call to Microsoft Support and more unhappiness when it is explained that the item has been removed from a database and is now irretrievable.

In their wisdom, Microsoft decided that it would be best to simply keep items in the Deleted Items folder around for as long as users want. Their logic is that this approach doesn't damage anyone as nothing is removed from mailboxes and users keep control of their data. All of which is true, but I still think it is madness because it encourages people to keep all manner of rubbish that should be removed from mailboxes as quickly as it arrives. But the size of mailboxes today are such that Office 365 can easily tolerate such slovenliness. After all, most users today are "pilers" rather than "filers".

As I pointed out in my article, the effect is that items will accumulate steadily over time as the Deleted Item folder swells. I calculated that I will have over 1 million extra items in my Deleted Items folder after a year, but have since been told that I am in the 1% category and can therefore be ignored for the purpose of the exercise. According to some sources at Microsoft, the majority of Office 365 users delete just 1,000 items annually. So there.

By the way, if you run a hybrid environment, you have to plan for what happens when bloated Exchange Online Deleted Items folders are moved back to on-premises servers. The Managed Folder Assistant running on Exchange 2010, Exchange 2013, and Exchange 2016 servers knows nothing of the desire to keep deleted items for ever and will cheerfully clean up the mess – after the mailboxes are moved back. This might be a problem for users if they have become accustomed to keeping everything.

Other courses could have been followed to achieve the objective of keeping deleted items for longer. It would have been easy to increase the retention period for the Deleted Item tag from 30 days to even 90 or even 365 days. The downside here is that altering a tag forces the Managed Folder Assistant to recrawl mailboxes to adjust the retention expiry stamped on items, and that's a lot of processing for the Exchange Online mailbox servers to do. It also means that other retention policies that reuse the standard Deleted Items retention tag would have been affected, so maybe this is not such a good idea.

A better technical solution might have been to increase the deleted item retention period. This is the time that items spend in the Recoverable Items folder during which items can be restored using the Recover Deleted Items option available in Outlook and Outlook Web App. The default period is 14 days and it can be increased by an administrator to 30. The period could have been adjusted to 365 days with no impact on the Managed Folder Assistant or great strain on servers. However, the downside is that the Recover Deleted Items function is not particularly user-friendly and the thoughts of trying to find something in tens of thousands of recoverable items isn't too appealing. Also, people who predominantly use mobile clients wouldn't be able to recover items because the function is available on no mobile client that I know. By comparison, the Deleted Items folder is available to any mobile client who cares to expose the folder to users.

People wonder whether they lose control when they move workload to the cloud. There's no getting around this because you do. You lose lots of control. This is one example of where change occurs because it's right for the majority but might not work for you. 

All in all, Microsoft made the best choice. I still don't like it, but at least it's a change that is easy to reverse. For that I am grateful.

Follow Tony @12Knocksinna