Microsoft Teams – Check Your External Sharing

External Users Cannot Open Content

You oversee a project which involves collaborating with some external entities. Easy enough you’d think. Your Teams settings allow external sharing, and you can add the external email address of the user with whom you are intending to collaborate.

The external user can successfully log in and can even see the folder structure, just the same as you. The trouble is that the external user can’t open any of the files and instead get the message as shown in this screenshot.

The administrators very diligently go through all of the Teams sharing and security settings, checking everything and they can’t find anything at all wrong in Teams at all. This had one of our customers in a very confused state and eventually they reached out to us to see if we had ever encountered the situation before.

The customer could not explain why their external collaboration partner could successfully log on to the Teams and also successfully see the folder structure that they expected.

We had the customer look into SharePoint and check their sharing settings there. Here’s where it all fell into place. The person with whom they were collaborating with was a private contractor and only used a Gmail address. At a previous stage, in response to a security initiative to restrict access to users with “consumer” identities they had locked down the domains with whom they were willing to share data.

As you see from the image below, the usual suspects had been blocked. This is an image subsequent to the removal of Gmail to allow this contractor to gain access to resources. Once the Gmail domain had been removed from the blocked list, and once the external user refreshed their view, they were able to open the files in the channel to which they had been granted access.

Lesson Learned

Always remember that your MS Teams environment may well increase collaboration opportunities but Microsoft 365’s security tentacles extend into places you may not initially expect. If you have an odd problem with Teams and OneDrive, there’s every chance that it’s SharePoint doing something that you aren’t expecting. Make sure SharePoint settings are in your troubleshooting list when looking at problems with Teams and OneDrive.

If you have any questions about sharing with external users on Microsoft Teams, please don’t hesitate to reach out to us. To learn more about our Productivity & Collaboration solutions, click here.