Why did my email messages disappear from my inbox?

While the Personal Archive mailbox in Exchange Online is a great feature for most end users, some folks become distressed when all of their old mail “disappears” from their inbox and mailbox folders.

By default, when you enable a Personal Archive mailbox, all mail older than two years in all primary mailbox folders will be moved to the Personal Archive mailbox. This is a result of a Retention Policy being applied daily to the mailbox.

You may find that two years isn’t long enough for a majority of your end users, so you want to extend the age of the items archived, or simply disable the automatic archiving. To do so, you’ll need to modify the default retention policy.

Out of the box, every Exchange Online mailbox has the “Default MRM Policy” retention policy assigned to it.


We need to find it the bit in the retention policy that moves mail to the Personal Archive (When the PA is enabled) from the primary mailbox after 2 years.

Go to compliance management >> retention policies.  Double click the “Default MRM Policy” to open the properties:


The retention policy properties window shows a list of retention policy tags and their actions.  We’re trying to identify the tag which archives the email after two years, so we want the one which has the retention action of “Archive”:


Now that we’ve identified the name of the retention tag being used to send items to the archive, click cancel to close the properties window, and then click retention tags in the top menu.  Double click the “Default 2 year…” retention tag to view the properties:


Alter the “Retention period” settings to increase or decrease the item age. You can also select “Never” to never allow the retention tag to move anything to the personal archive.  Just to be tidy, if you change the item age, modify the retention tag name to reflect the new item age. Click save to save these changes:

image clip_image011

Why don’t we simply delete the retention tag instead of setting the retention period to “Never”? It’s a personal preference. I don’t like to delete default settings. Deleting the tag would have the same effect.

Note: Altering the archive retention tag won’t restore archived mail to the primary mailbox if the retention policy previously ran against a mailbox. Mailbox users will have to manually move the archived items back into their primary mailbox if that’s what they want to do.

See Retention Tags and Retention Policies at Microsoft TechNet for more detailed information.

Barry Thompson
Principal Consultant – Cloud Solutions

One thought on “Why did my email messages disappear from my inbox?

  1. Hi, having read the above and many googled explanations about outlook and the “lost” emails, I still don’t understand how this works. I’m using Outlook 365 which I got a couple of days ago. I can do most things I was able to do in the earlier versions, and I get more used to it as I go along. BUT I still find that emails in my inbox “disappear” a few seconds or minutes after I have read them. I can get round it by marking them as unread or moving them to a folder I have created which I call “my-inbox” (or both) but this seems illogical to me. Why can’t they stay in the original inbox until I decide to move or delete them? Why does Outlook make decisions for me? Also, I fail to see the logic behind having “sent items” as a subset to “inbox”. Can anyone explain these things to me? I would be very grateful.


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