Room Resource Sharing with Guest Users

Question

Hi,

I'm trying to share the organisational room resource with external user. I was testing with my personal account but It seems I couldn't see the option "Add from Directory" on my personal Microsoft Outlook account - Do you think that option is only available on work or school account?

Also, May I confirm that as long as the external user has work account, we can share the Room Resource with them right?

Thanks

Answer 1

Hi there,

Thanks for your suggestion. I can confirm:

Step 1: Tenant External Calendar Sharing Settings => Done

Step 2: Exchange Online PowerShell Configuration (for direct booking/processing) => Done

Step 3: Sharing the Room Calendar Directly => Done

After a few testing that I made, If I sent an invitation using my personal account, it would reflect on the room resource's calendar for everyone to view it. However, If one of organisational members sent invitation to the calendar, it did not sync/reflect to my personal account - I left the calendar overnight and checked again this morning but couldn't see any events apart from the events sent from my personal account. There is only one-way view as we want everyone including both internal and external users are able to view full details/events on the calendar

If we can find a way to fix this, it would be great!! Otherwise, I would think of adding my personal account as guest user which I did for testing purposes. When I followed the invitation link sent from my organisational admin account, I seemed not to be able to log in Outlook using Microsoft personal account, it said need to be with work or school account :)

Please let me know what your thoughts regarding this. Thanks

Answer 2

Dear @Minh Vu

I am happy to assist you with your questions regarding sharing Room Resource calendars with external users in Microsoft 365.

Question 1: Is the "Add from Directory" option only available on Work or School accounts?

Yes. The "Add from Directory" option is exclusively available to Work or School accounts (Exchange Online / Microsoft 365 Business or Enterprise). Personal Microsoft accounts (such as ⁠@outlook.com⁠, ⁠@hotmail.com⁠, or ⁠@live.com⁠) do not connected to an organizational Global Address List (GAL) / Directory, so they only have access to personal contacts.

Question 2: Can we share a Room Resource as long as the external user has a work account?

Yes, but with specific administrative requirements. An external user with a work or school account can view room availability or reserve room resources, provided your tenant administrator configures Exchange Online correctly.

By default, Room Resources drop external booking requests to prevent unauthorized access. To enable sharing or external booking, the following conditions must be met:

Step 1: Tenant External Calendar Sharing Settings

The Microsoft 365 Global Administrator must allow external calendar sharing in the admin portal: 

Navigate to Microsoft 365 Admin Center > Settings > Org settings > Services > Calendar. 

Enable "Let your users share their calendars with people outside of your organization who have Office 365 or Exchange". 

Please refer to this document: Share Microsoft 365 calendars with people outside your organization

Step 2: Exchange Online PowerShell Configuration (for direct booking/processing)

If you want external users to invite the Room Resource directly in meeting requests, an administrator must update the Room's ⁠CalendarProcessing⁠ settings via Exchange Online PowerShell:

Set-CalendarProcessing -Identity "******@yourdomain.com" -ProcessExternalMeetingMessages $true

Note: Setting ⁠-ProcessExternalMeetingMessages $true⁠ enables the room to process and accept/decline meeting invites sent directly from external email addresses.

Please refer to this document about step by step code: Set-CalendarProcessing

Step 3: Sharing the Room Calendar Directly

If external users need to view the room's schedule/free-busy status in Outlook:

• Assign an internal user Full Access or Delegate rights to the Room Resource. 
• Have that delegate open the Room's calendar via Outlook on the web (Open another mailbox). 
• Share the Room calendar directly with the external user's email address and set the desired permission level (e.g., Can view when I'm busy or Can view all details). 

Please refer to this blog about same your question: Sharing Office 365 Room's availability to external users

Please let me know if you need assistance with specific PowerShell commands or setting permissions for your resource mailboxes.

---

If the answer is helpful, please click "Yes" and kindly upvote it. If you have extra questions about this answer, please click "Comment".   

Note: Please follow the steps in the forum document to enable e-mail notifications if you want to receive the related email notification for this thread.