CU policies require throttling sends to large audiences that occur during business hours at a rate of no more than 18,000/hour (or five messages per second) to avoid overloading CU's servers. Learn how.
Transferring a license? Adding a new user to an existing team? Create a report of the events created by a particular user. That way you have a list of events to share with the new person, so they can hit the ground running.