The thing to do would be to lift messaging out of the forums; then they could build it from the ground up, with input from the community.
“Subscribe”, “unsubscribe”, “ignore or vacation”, and “follow (this one message)” modes could then all be instigated; plus categorizing, organizing, saving, and deleting could then be all very specific to the messaging system. I don’t think anyone would ever regret moving messages out of the forum system of topics.
Quote from FA Moore
I thought it was worth mentioning to the general populace….the messaging system for groups is VERY broken….