I think it would be a great idea to allow messages to be cc'd with a limit of 7 people.
For example, in Diablo 2, you can have 8 people in a game. Say you are rushing people, you could send the game name/pass in 1 message to 7 people.
Say you post a thread and you're trying to buy a bunch of common items. Instead of sending 7 individual messages, you can send 1 message to 7 people at once.
It would be a nice quality of life update in my opinion