Invitee Limits for Teams Meetings Scheduled through Outlook
An update is coming to Outlook which will prevent more than 750 people from being invited manually to a Teams meeting. (This refers to the process of adding email addresses one by one to a Teams meeting invitation in Outlook.)
After June 2021, Outlook users will see an error message when trying to schedule or reschedule a meeting with more than 750 invites. A Distribution Group should be used to invite over 750 people to a Teams meeting.