Change to Outlook Groups Displays High Unread Counts

Wow! Where Did All Those Unread Items Come From?

Last Tuesday, I checked for updates for the Microsoft 365 apps for enterprise (Office click to run) and duly downloaded the available update to upgrade to version 2009 (build 13231.20200). Nothing strange happened and the upgrade proceeded without any issues. I was a happy camper.

That is, until I noticed that the unread count for my Outlook Groups suddenly displayed much higher numbers (Figure 1). Usually these groups have a very low number of unread items, especially those marked as favorites because I check them at least once daily.

Outlook for Windows displays some high unread counts for Groups
Figure 1: Outlook for Windows displays some high unread counts for Groups

The History of Groups

The reason why this happens is clouded in history. When Microsoft introduced Office 365 Groups (now Microsoft 365 Groups) in November 2014, they were characterized as a new way for email-centric collaboration. Teams didn’t exist at that point and although Microsoft’s marketing muscle was pushing Yammer (bought in June 2012) as the future for collaboration and a replacement for email (that strategy really worked out), the bulk of interpersonal electronic collaboration occurred over email.

In the on-premises world, many Exchange organizations combined distribution lists with public folders to give people an archive for discussions. Groups introduced a group mailbox to host discussions and a shared calendar and came with a SharePoint Online team site for document storage, including a shared group OneNote notebook. Given that the bulk of work that had been migrated to Office 365 at that point was email, Groups looked pretty good. In April 2017, Groups (now called Groups in Outlook) had 10 million active users, or roughly 10% of the Office 365 user count at the time. The latest figure for Office 365 is 258 paid seats (April 2020). It’s unlikely that Outlook Groups have kept pace and now has 25 million active users, but it’s possible.

The collaboration landscape within Office 365 changed upon the general availability of Teams in March 2017. Since then, Teams has taken the lead and Groups have concentrated on a new mission of delivering a membership and access service to applications like Teams. Usage of Outlook Groups as a fulcrum for email-based collaboration is much less important to Microsoft now, but Groups are still actively used in this way in many Office 365 tenants.

Choosing a Simpler Unread Count Model for Groups

When Groups were added to Outlook in 2015, the developers decided not to use the standard item read/unread model as used in other mailbox folders like the Inbox. This model depends on the unread status of items and operates on a per-user basis. In other words, in a shared resource like a group inbox or public folder, each user has a separate unread count generated by the number of items they have not read in the folder.

Instead, the group developers chose a “more simple triage model for the groups conversations list, where all the conversations would be marked as seen as you moved away from the group.” Apparently, the decision was based on user feedback that many groups contain conversations unimportant to some members, so you couldn’t expect them to read everything. As implemented in Outlook, the group seen/unseen model allowed users to scan a group for new items and then set the unread count to zero once the user moves from the group. The new item count for a group then becomes the number of items delivered to the group since the last access by the user.

By comparison, new messages delivered to an inbox are personal and the mailbox owner is expected to deal with them. The new item count for the inbox is therefore very important for the mailbox owner and is adjusted up and down as the unread status for messages change (you can mark a read item as unread).

OWA and Outlook Mobile Use Normal Unread Counts

At the time, the developers accepted that the difference in how folders reported unread counts caused user confusion and said that they were working on implementing an item read/unread model for Groups. That model was implemented by OWA in early 2019 and is in use today (Figure 2).

OWA has used the read/unread model since 2019
Figure 2: OWA has used the read/unread model since 2019

For whatever reason (prioritization, lack of resources, more pressing features, etc.), Outlook desktop is a long way behind OWA in moving to the item read/unread model. The latest builds of Outlook have switched to the item read/unread model, which is the reason why the unread counts for my groups suddenly exploded from their normal low levels. Outlook Mobile has also used item unread counts since early 2019.

Resetting the Unread Count for an Outlook Group

Another piece of good news is that the Outlook developers have included a Mark All as Read option to reset the unread count for a group. Select the group you want to reset, right-click, and select the option. Processing to reset the unread status for items occurs in a background thread, so it doesn’t stop you working while the unread count is reset. Depending on the number of unread items in the group, the option can take a little while to complete.

Outlook's Mark All as Read option
Figure 3: Outlook’s Mark All as Read option

Unhappily, Outlook’s Mark All as Read option might not be able to update the status for all unread items. At least, it didn’t for me. My solution was to open the group with OWA and use its version of Mark All as Read, which worked flawlessly.

The good news is that as you open unread items in in a group using one client, the read status for the item and unread count for the group is updated and shown correctly across all Outlook clients.

Hindsight Always Best

The benefit of hindsight tells us that the decision of the Groups developers to go with the simpler read/unread model for their Outlook implementation was flawed. The change made in the other clients in 2019 is now showing up in Outlook desktop. A little preparation and user communication should be enough to get everyone over the shock of seeing elevated unread counts for their groups.


This one-time change will probably warrant a line or two in the Office 365 for IT Pros eBook. It’s an example of a small change that’s important for some users for a period. Once the change is done, it’s done. But change persists inside Office 365, which is why we keep updating the book.

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