How to stop outlook from opening a browser every time I create a meeting?

I'm having a similar issue where every time one of our users clicks on an email (seems random as to which ones it happens on) it opens the OWA for that account.

I'm having the exact same problem for myself and several of my company's staff. Not specifically with meetings, but as you said, just reading an email (not even clicking on anything) can cause this to open and it's infuriating. We also block OWA, so the window will never load. The link it's trying to open seems to be to do with activity feeds, https://outlook.office.com/opx/******@companyname.org.uk/activityfeed/?hostApp=outlookdesktop&culture=en-US.

I'm going to try the regedit someone over on Reddit posted to see if it'll help here even though mine's activity feed rather than meeting room-related, even if it's only a short term fix. For anyone that has Reddit blocked and can't access it at work at work, what they suggested was:

1. In Registry Editor, navigate to: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Options\Calendar
2. Right click on Calendar and select New DWord (32-bit) value.
3. Set the Name to ShowLegacyRoomFinder and press Enter.
4. Right click the new key, select Modify and set the Value data to 1.
5. Close Registry Editor and restart Outlook.

Posted by someone called Barakta over on Reddit.

*Edit* the regedit above does not work, Outlook continues to try to open OWA as per the above link :(

FYI

The registry change did work for me on Multi-session host with Office 365 Shared activation

For the original problem relating to meetings opening the OWA link it does resolve the issue for the moment. If it is not helping with your issues I would recommend opening a support ticket in your admin portal if you can. More tickets means more focus on the issue.

Have done. Since there's nothing to do with this coming up in my searches, I'll check back here and update here if I get anything useful out of them even if it's not entirely the same as the original issue.

I wish you luck with your issue. Hopefully it will boost the issue overall since the current bandaid doesnt work for you and prevent the issue from being set aside and left with just a registry key change.