How to prevent meeting organizers from cancelling meetings using the clients Outlook Desktop and OWA?

Rib 20

Hello,

In a Hybrid environment O365 and Exchange 2019, we currently use an internal app for specific organizers to create and cancel meetings sent to specific set of 15 rooms, we would like to prevent organizers from cancelling these meetings from Outlook desktop and OWA.

We have no problem when it comes to sending out the meeting to these specific rooms and the attendees, the issue is only with the cancellation. The rooms have a delegate managing reservations and so he's also receiving cancellations notifications but with no button to decline (like we have when booking the rooms).

The headers (of the cancellation messages) look similar either when cancelling from the internal app or Outlook/OWA, I can't really use a transport rule.

Is there maybe a way using Graph API and/or Conditional Access that can help block cancellations made via the clients (Outlook and OWA) towards these rooms?

Thank you so much for you help.

Best regards

1 answer

Mike Hu-MSFT 4,135 Reputation points Microsoft Vendor

2024-08-22T09:00:41.82+00:00

Hi,

Welcome to the Microsoft Q&A forum!

Based on my personal experience,there is no such built-in function to achieve this. The way Exchange assigns meeting permissions is based on accounts and roles, and different permissions can only be assigned to different accounts.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.
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Rib 20 Reputation points

2024-08-22T09:13:06.7733333+00:00

Hi @Mike Hu-MSFT Could you please elaborate on this part: "The way Exchange assigns meeting permissions is based on accounts and roles, and different permissions can only be assigned to different accounts." Thanks a lot

Mike Hu-MSFT 4,135 Reputation points Microsoft Vendor

2024-08-23T06:14:40.4933333+00:00

Hi,

Good day, you can refer to https://learn.microsoft.com/en-us/powershell/module/exchange/set-calendarprocessing?view=exchange-ps

ResourceDelegates: Specifies the delegated roles of the room resources that can handle booking requests on behalf of the room.

This means that when you delegate this permission to a user, this user can handle requests to book a conference room on behalf of the conference room, whether using your internal program or Outlook or OWA. You cannot achieve this: the user can handle meeting booking from your internal program but not from Outlook or OWA.

Rib 20 Reputation points

2024-08-23T08:48:38.3+00:00

Hello @Mike Hu-MSFT , thanks a lot for your answer, I already know that there isn't a built-in option in Exchange Online to achieve that, I've also looked at the properties of the calendar processing, but I'm looking for a different way to do it, the main goal is to block cancellations of meetings coming from a specific app/client like Outlook or OWA or somehow to moderate them.
I understand you say that it's not possible in EXO, but can we think of any other way outside of EXO?

Thank you
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How to prevent meeting organizers from cancelling meetings using the clients Outlook Desktop and OWA?

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