Join button missing on Lync Meetings from federated partners

You might have the situation that you are receiving Lync Meeting invites from federated partners using Exchange 2013 and Lync 2013, but when Outlook 2013 or OWA 2013 CU1 brings up the reminder dialog for the meeting, the Join button is missing. Outlook and OWA will show the Join button based on the existence of the MAPI property OnlineMeetingExternalLink on the calendar item representing the meeting in the attendee's mailbox.

It is the Lync Meeting Outlook add-in used by the organizer of the meeting, which sets the property on the meeting invite, before it is sent. However the MAPI property might be stripped from the message, when it is sent from the organizers Exchange 2013 environment to your, i.e. the meeting attendee, Exchange 2013 environment. You need to ensure that in the organizer's Exchange 2013 environment, the remote domain matching your Exchange 2013 environment, has the parameter TNEFEnabled set to True ( When TNEFEnabled is set to true Exchange 2013 does not strip MAPI properties including OnlineMeetingExternalLink and the Join button will be shown on the reminder.

Let us assume that the SMTP domain of the attendee is In the organizer's Exchange 2013 environment it is necessary to create a remote domain with TNEFEnabled = True representing One way of doing it is by using the following commands in Exchange Management Shell:

  • New-RemoteDomain -Name -DomainName
  • Set-RemoteDomain -Identity -TNEFEnabled:$true
Comments (2)
  1. Sai Prasad says:

    Nice post Jens..

    After reading through this, I went up to set the property and did it through Shell.

    Looks like remote domain management is not possible for now (until CU2) in 2013 through EAC.

  2. Jordan Nolan says:

    This article was extremely helpful in solving an issue I had with our Skype for Business based video conference phones. We are using the Polycom Trio 8800 units which worked perfectly for site to site calls within our domain, but when we tried to schedule meetings accross our O365 tenants to our sister companies who have their own tenants, the meeting invites would not register properly on the remote video phones.

    As described, crossing the domains strips out the MAPI content so the content in the meeting that the phones relied on was stripped out. Setting up the TNEFEnabled resolved the issue. Now we can schedule video conferences accross domains to all our sister companies with easy.

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