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Different SharePoint Folder Used to Hold Email Sent to Teams Channels
Being able to send email to a Teams channel is a very convenient way of starting a new channel conversation based on information received in email. I also use the feature to archive messages sent to Exchange Online distribution lists by creating a mail contact object for the channel and including the mail contact in the list membership. This method also works with Microsoft 365 groups by using an Entra ID guest account instead of a mail contact.
Messages received by the Teams channel show up as individual conversations and are also stored in a SharePoint Online folder. In 2021, Microsoft changed the storage location in SharePoint for these messages without warning. The logic for the change was reasonable. Instead of using a single folder to hold all the messages received by a channel, Teams created a new folder every month to store the messages for that month, so you ended up with folders like EmailMessages_11_2025 under the base folder created for the channel.
Unannounced Changes Can Cause Problems
The change in folder structure was technically good and avoided the potential performance problems that can occur when SharePoint Online must deal with tens of thousands of items in a folder, such as exceeding the list view threshold. However, making changes without publishing details to customers is not a good thing to do. For instance, when the folder structure change happened in 2021, some customers complained that it interfered with triggers they had built into Power Automate flows.
The Latest Change to Folders Used for Email Sent to Teams Channels
Well, the same thing happened again. At least, a change to the folder structure rolled out to tenants between January and February this year. I guess I wasn’t checking SharePoint folders as carefully as I should have. I also completely missed Microsoft 365 message center notification MC981626 (published January 16, 2025) where Microsoft published the news with the title “New file path in Microsoft SharePoint for email attachments.” The text of the notice says: “As part of our ongoing security improvements, we are updating the storage path for attachments sent from any email client using the Send an email to a channel in Microsoft Teams feature in Teams.”
The text in MC981626 is a little misleading in that it could be read as only applying to email attachments. However, the change applies to all messages sent to Teams channels and moved the creation of new folders to hold the copies of email sent to channels from:
Documents – Channel Name
To:
Documents -> Apps -> Microsoft Teams Mailhook -> Channel Name
Older folders used to hold email sent to Teams channels prior to the change remain in their old location. I’m not sure how the new structure improves security unless everything is better when files are stored in an obscure location several levels deep.
Figure 1 shows a typical set of folders created since the change went into effect in January 2025.
Although Microsoft issued a message center notification, not everyone is an avid reader of what appears in that section of the Microsoft 365 admin center and the change took some by surprise. Here are two examples involving files not appearing in Teams after being scanned and someone wondering why a workflow failed because files didn’t turn up in the expected location.
Important to Stay in Touch
All of this proves that tenant administrators need to pay more attention to the news that appears in the message center. I know everyone will say that they do, but I’ve heard from Microsoft sources that their telemetry says that a large percentage of tenants don’t read message center notifications.
My advice is to use the Planner integration with the message center to track and assign tasks relating to upcoming changes. We do this to track updates for the Office 365 for IT Pros eBook. I just missed out on the task generated for MC981626 that was assigned to me (my only excuse is that too many tasks end up being assigned to me).
So much change, all the time. It’s a challenge to stay abreast of all the updates Microsoft makes across the Microsoft 365 ecosystem. Subscribe to the Office 365 for IT Pros eBook to receive insights updated monthly into what happens within Microsoft 365, why it happens, and what new features and capabilities mean for your tenant.
Is there a risk of emails to channels poisoning copilot responses? This doesn’t look like it would help with that though. Also, what else is going to go in the apps folder? A folder with a single folder makes no sense.
I’ll admit I very much dislike the Documents folder getting cluttered with years of email folders, so moving it down a level makes sense, but moving it down 3 levels less so.
Messages captured in SharePoint Online are available to Copilot, so yes, they could affect the content of responses unless the site is excluded from Copilot processing.