You are now able to control when notifications for onboarding tasklist are sent.
When using the onboarding all notifications for tasklist are blocked until one of two things happen:
1.) You invite the person being onboarded
2.) You click "Activate notifications" in the header of the tasklist
This does not effect tasklist activated via People -> Actions or Offboarding tasklist.
You can double check any tasklist you are part of via the Task tab in your main menu. As a tasklist owner you'll find all your active tasklist via Settings ->tasklist -> Show active tasklist.