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dynamically share a resource mailbox (calendar) between two organisations

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Occasional Contributor

Is it possible to dynamically share a resource mailbox (calendar) between two O365 organisations (domain) like a normal mailbox?

9 Replies
Define "dynamically"? You can share calendars/set up org relationship, but that only covers "read" mode.

@Vasil Michev 

I want to share a meeting room calendar with someone who is in another organisation.
There is already a relationship between the organisations.
Unfortunately the calendar sharing option is not active (automatically updated).
I can only send the current status of the calendar by email (not automatically updated).

If you have org relationship in place already, you only need to adjust the permissions on the calendar folder. No need to "share" the calendar. If for whatever reason you do want to do that, you need to configure the room mailbox as additional account in Outlook in order for the button to be enabled.

@Vasil Michev I can only add permissions for people in my organisation.
If I add the calendar as an additional account I can only send the calendar by e-mail.

 

best response confirmed by vinzcraft (Occasional Contributor)
Solution
It's the "Default" permission entry that is used, just make sure that it is set to LimitedDetails (well, anything other than None should do).
Again, there is no need to "share" the calendar if you have an org relationship in place, the Default ("standard"?) permissions already allow people on the other side of the org relationship to view it.
If you do want to share it for some reason, you need to add it to Outlook as additional account. To do that, you need Full Access permissions granted. Then follow the steps here: https://www.michev.info/Blog/Post/2025/how-to-add-a-shared-mailbox-as-additional-account-in-outlook-...
after some time of synchronization it works.
The rights for standard /Default were not good.

Can I remove the rights for anonymous?
Yes, anonymous shouldn't matter.