How to stop the email notifications popping out to users when migrating the Task Assignments ?
Go to the Existing plan in the target tenant -> Click on more option (…) -> Plan Settings -> Unselect both settings under “Have Planner send me notifications when”. Every user who want to disable the notification has to repeat the above steps by logging into the Planner.
Reference link : https://support.microsoft.com/en-us/office/plan-members-manage-group-emails-for-your-planner-plans
Note : However, we can’t avoid these notifications, when migrating the tasks to a new plan.
