Outlook’s Strange Archive Folder

Five Years On, the Use Case for the Archive Folder is Still Unclear

Generally, I am positive about the changes that Microsoft makes in Microsoft 365. Well, maybe we complain about some of the updates. From time to time, Microsoft throws some curve balls to cause me to scratch my heads. For instance, the time when they decided that it would be a great idea to create Microsoft 365 group for each manager with the manager’s direct reports as the group members. Anyone concerned with privacy could see that was a bad idea. Fortunately, that bright spark fizzled out quickly.

The Odd Archive Folder

Which brings me to Outlook’s strange Archive folder. This appeared in March 2017 and promptly caused massive confusion with Exchange Online’s archive mailboxes.

Microsoft’s support documentation says:

There are several ways to archive messages in Outlook. The methods that you can use depend on the type of email accounts that you have set up in Outlook.

All accounts have access to an Archive folder. For Microsoft 365, Outlook.com, and Exchange accounts, the Archive folder is one of Outlook’s default folders, like Inbox, Sent Items, and the Deleted Items folder. This folder can’t be deleted. If you use Outlook with an Exchange or Exchange Online account, folder policies such as retention policies apply to the Archive folder.”


Using the Archive button to move messages to the Archive folder doesn’t reduce your mailbox size.”

This description makes it seem like someone thought that it would be convenient to give users an Archive button to move items into the Archive folder as some sort of primitive file-out-of-sight mechanism. I don’t see any trace of the Archive button in my version of Outlook for Windows in either the classic or simplified ribbon. Perhaps competition for space in the ribbon from new-fangled options like Viva Insights caused the Archive button to drop out. Who knows?

After five years of ignoring the Archive folder, I’m still not sure why Microsoft thought it would be a good idea to add an Archive folder to everyone’s mailboxes, but there it lingers today. The only reasons I can see for its existence are:

  • The Archive folder is available to mobile clients whereas no mobile client can access items in an archive mailbox because of the lack of protocol support in Exchange ActiveSync or Outlook Mobile.
  • Outlook can synchronize items in the archive folder for offline access.

However, these reasons are undermined by the simple fact that keeping items in other folders in the primary mailbox gains the same advantages. There’s no need to move items into a special folder to be able to access them on mobile clients or offline.

The archive folder is like your appendix. It’s there, no one really knows why it is there and you probably wouldn’t miss it if it wasn’t there.

Confusion with the Online Archive

From an administrative perspective, the big issue with the Archive folder is that it muddies the water with Exchange Online’s online archive. The online archive exists as a place where old messages go to rot until the organization is sure that no conceivable reason exists for them to be retrieved. Items in the online archive are indexed and available for eDiscovery. By comparison, the Archive folder is in the primary mailbox and has nothing to do with the online archive.

Items move from the primary mailbox to the online archive (archive mailbox) when:

  • A user moves items explicitly using a client like Outlook. This accounts for 0.000000184% of all items that reach archive mailboxes (I made that figure up, but it’s defendable).
  • The Exchange Managed Folder Assistant moves items because they have an archive tag assigned by the user or because a default archive tag exists in the mailbox retention policy assigned to the mailbox.

Only Exchange mailbox retention policies include tags with move to archive actions. Microsoft 365 retention policies can remove mailbox items, but they cannot archive the items.

Automatic policy-driven movement of items from primary to archive mailboxes is the right way to keep messages for the long term. The Managed Folder Assistant processes mailbox retention policies (including the move to archive) while a separate assistant applies Microsoft 365 retention policies to other workloads.

Stopping the Backspace Key Archiving Items

One interesting pointer from the support documentation is that if you use the Microsoft 365 apps for Enterprise (Outlook click to run), the backspace key moves the selected item to the Archive folder. I never knew that this happened, but it accounts for why items unexpectedly turn up in the folder. Usually, I just scratch my head and delete the mystery items, but it now seems that I put them there by pressing the backspace key!

To disable this one-click-to-archive behavior, update the system registry to add the DisableOneClickArchive DWORD value at HKEY_CURRENT_USER\SOFTWARE\microsoft\office\16.0\outlook\options. Set the value to 1 to stop the backspace key moving items to the Archive folder (Figure 1).

Updating the system registry to stop Outlook moving items to the Archive Folder
Figure 1: Updating the system registry to stop Outlook moving items to the Archive Folder

The backspace key will start to behave properly the next time you restart Outlook. This fix isn’t available for the perpetual versions of Outlook like Outlook 2019 and Outlook 2021. It’s just another example of the gap between the Outlook perpetual and Outlook subscription versions. The fix doesn’t work for the current beta version of the Outlook Monarch client, which merrily moves items to the Archive folder with the backspace key. Oddly, OWA doesn’t move items with the backspace key.

No Joy in Archive Folder

No good reason exists for the Outlook Archive folder. It is what it is and is probably going to persist for the foreseeable future. The best thing to do is to ignore the folder, that is, after you stop Outlook putting items into the Archive folder with the backspace key.

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