MC251564 – Updated June 16, 2021: Microsoft has updated the rollout timeline below. Thank you for your patience.
Within the desktop app in-meeting experience, organizers can choose to lock their meetings to prevent subsequent unwanted join attempts.
Users attempting to join a locked meeting by any means (e.g. from web, desktop, mobile, PSTN, and devices) will not be able to do so. There will be a message to say that the meeting is locked.
This message is associated with Microsoft 365 Roadmap ID 80669
When this will happen
Microsoft will begin rolling out mid-June (previously end of May) and expect to complete by the end of July (previously mid-June).
How this will affect your organization
When the change has rolled out meeting organizers will have the option to Lock the meeting:
What you need to do to prepare
You may consider updating your training and documentation as appropriate.