Symptoms

Add-ins button greyed out on Outlook for Mac. New add-ins in their Outlook for Mac install. You take a look and see the button is either non-existent or greyed out. The Teams Meeting button in Outlook for Mac will appear in the Outlook for Mac ribbon if Outlook is running production build 16.24.414.0 and later and is activated with a Microsoft 365 or Office 365 client subscription. The meeting coordinates (the Teams join link and dial-in numbers) will be added to the meeting invite after the user clicks.

In Outlook 2016 for Mac or Outlook for Mac 2011, you cannot accept a New Time Proposal from an attendee. The New Time Proposed email message displays one of the following messages:

<Attendee Name> has tentatively accepted, but proposed that you change the meeting time and then send an update.
Proposed new time: <Date, time>

<Attendee Name> has declined, but proposed that you change the meeting time and then send an update.
Proposed new time: <Date, time>

Cause

The Propose New Time feature is not available in Outlook for Mac 2011 and Outlook 2016 for Mac versions 15.8.2 and earlier. Users who have these versions of Outlook for Mac will be unable to accept a proposed new meeting time without manually modifying the meeting request.

Resolution

The Propose New Time feature is available in Outlook 2016 for Mac version 15.9 and later versions when you are connected to Microsoft Exchange Server 2013 Service Pack 1 (SP1) or a later version.

To use this feature when a new time proposal is received, open the New Time Proposed message, and then select the Accept Proposal or View All Proposals button.

Note

If you are running Outlook 2016 for Mac version 15.9 or a later version and you are connected to a version of Exchange Server that's earlier than Exchange 2013 SP1, the Accept Proposal and View All Proposals buttons do not appear.

Workaround

This workaround applies if either of the following conditions is true:

You are running Outlook for Mac 2011 or Outlook 2016 for Mac version 15.8.2 or an earlier version.
You are running Outlook 2016 for Mac version 15.9 or a later version and you are connected to a version of Exchange Server that's earlier than Exchange 2013 SP1.

Outlook For Mac New Meeting Greyed Out Video

To work around this issue, open the meeting from your calendar to modify the time, and then send the update to the attendees.

Outlook For Mac New Meeting Greyed Out

More information

Outlook For Mac New Meeting Greyed Out Iphone

For more information about proposing a new time in Outlook for Mac, see You cannot propose a new time for a meeting in Outlook for Mac.