Microsoft Teams opens meetings in the default web browser instead of in the Teams app.

[howie_isaacks]

I'm hoping someone here has encountered this issue and solved it. I'm at a loss for how to fix this.

One of my users has an issue with joining Teams meetings from within Teams. When he clicks join, his default browser opens. If he has Chrome set to be the default browser, he can click the option to open Teams and continue joining his meeting. If Safari is set to the default browser, he can't join the meeting. Obviously we want for Teams to not trigger a browser to open. It should just join the meeting from within the app.

Here are the things I have tried to solve this: 

1. Log out his account and the log back in.

2. Use the Teams reset tool from Microsoft.

3. Completely remove Teams using a tool called AppCleaner which will find all of the settings, caches and other miscellaneous files associated with Teams and delete them along with the app. Reinstalled Teams after this.

I have searched for this issue in the Microsoft support community but all I have found are a lot of me too posts and no solutions. I think that there is some default setting that is causing this but I don't know where to look for that.

[Anonymous]

@howie_isaacks   Hi Howie, I tried to play the scene, you described. I noticed, that there are two possibilitied, to join a Teams® Meeting:
1st, you can join with a click on "join now" at the reminder (the message widget from apple) -> this will open a browser (the default one).
2nd, you can join by opening the meeting date in Outlook® and clicking to "join now". -> this will open the Teams® app.
This behavior was on my Macbook, when I was in my office. 

I didn't find any way to configure, how to open the meeting links only with the Teams® App.

[howie_isaacks]

I'm going to reach out to Microsoft about this. On every other Mac that I take care of, users can just click the join button from Teams and it joins the meeting. No browser is opened. That's the way it's supposed to work. The issue I know I will run into is that Microsoft's support for Mac software sucks.

[Anonymous]

@howie_isaacksdo they join from MS Teams® direct or do they join in one of my described ways upper?
Honestly, I did not test to join direct via MS Teams®, I will make up for it.

[howie_isaacks · Accepted solution]

What was causing this was the link protection feature in Mimecast. All of this user's email first passes through Mimecast before it goes to his Microsoft 365 inbox. Therefore, the meeting invitations that he receives are tagged with the extra code from Mimecast. If we turn off the link protection feature temporarily and then send him another meeting invitation, it works properly in Teams. I know that the Microsoft 365 link protection feature does not do this so we can switch him to that and stop using the feature in Mimecast.