This group within the Episcopal Church had an internal email distribution system for many years. When they updated their web site and introduced a new online service, they needed a way to distribute emails created in the internal, proprietary system to new external subscribers.
They ordered a CCtoMany address, and added it to their internal distribution system.
Now anything sent to the internal distribution address is copied to that CCtoMany address and thus to everyone on their CCtoMany list!
Problem solved!