Unable to join forwarded External Teams Meetings to MTR

New Contributor

Hi Everyone


We have an issue whereby the MTR does not allow you to join any forwarded external Team meeting invites.   The resource mailbox will accept the invite however when you go to the meeting room the JOIN button is not there.


If the invite is sent directly from the external we will be able to join the meeting in the MTR.


We use Crestron Flex.   We have changed the settings in Proofpoint so that the URL is not overwritten, enabled the resources to accept/decline external meeting invites however we are still having the same issue.   


Any help would be greatly appreciated.

9 Replies
This could be to do with Transport Neutral Encapsulation Format (TNEF). I thought this issue was largely resolved but it may still be related. These articles might be helpful - http://blog.schertz.name/2019/08/exchange-resource-mailbox-configuration-for-meeting-rooms/. https://docs.microsoft.com/en-us/skypeforbusiness/deploy/deploy-clients/room-system-and-federated-pa... Set-CalendarProcessing -Identity ABC@Contoso.com -DeleteComments $false New-RemoteDomain -DomainName Contoso.com -Name Contoso Set-RemoteDomain -Identity Contoso -TNEFEnabled $true Let me know how you get on.

@MJBuxton When I'm using Outlook application and forward to MTR systems I always remove the text in the top of the message since I had the same problem as you a long time ago when I didn't remove this text. I'm not sure if you have to remove that anymore and I rarely use Outlook application (use web app instead) so I can't say for sure.

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Sounds like the invite is getting messed up. This can also happen for Guest Join Access for Webex. Check out the docs here https://docs.microsoft.com/en-us/MicrosoftTeams/rooms/third-party-join
Thanks everyone. We found that we had to turn this on which means that externals can book your meeting rooms <sigh>

@MJBuxton What exactly did you turn on?

@MJBuxton I'm having the same issue.

What exactly did you turn on?

@Askanison  Set-CalendarProcessing -Identity YourResourceMailboxMailid@YourDomain.com -ProcessExternalMeetingMessages $True  -  It will enable external domain to book your organization's meeting room.

What do you mean by removing the message at the top?
Sorry to resurrect an old thread but I think there is some confusion about the issue at hand here.

The OP complained that forwarded invites result in the meeting room kit not resolving the fact that it's a joinable meeting. The first suggestion may fix this, although I can't verify right now.

The ProcessExternalMeetingMessages flag is completely separate and simply enables the mailbox associated with the meeting room kit to automatically accept calendar invites, exactly as it would for internal invites.

Did anyone successfully fix the problem the OP had? I'd be interested to hear as this causes us massive grief.