Custom Chat Rooms
A great idea is to have group discussions. If there was a way to have a chat room in game with only certain people in your clan, communication would be a lot easier. For example, as clan leader I would like to talk with my Elders and my Elders only about a merge. Instead of mailing each one of them individually, we could have a chat room and talk all at once. Communication would be easier, and it would be a lot more convenient.
Maybe you could create chat rooms and invite people to them, or some form of creation of chat rooms.