For quite some time, Outlook clients have been showing a Join button to join a meeting, especially when using Teams for the meeting but also for other meeting providers, such as Zoom.
While most of meeting providers integrating with Outlook should have been using HTTPS connection, there may still be some still not using HTTPS connection for joining the meeting; most likely not because the provider does not support HTTPS but customer side configuration.
Well, starting November 2026 – with a completion date expected to December 2026, Microsoft is enforcing the use of HTTPS to join a meeting and as part of this enforcement, if the Join meeting link is NOT using HTTPS the Join button in Outlook will disappear.
For most customers and meeting providers, there should be no impact or change in configuration but if your end-users start to see the Join button disappearing, it would be a good thing to double check your meeting provider configuration to ensure it is using HTTPS for meetings