phatomk, you can always go and reupdate and add new ideas to the current mod Admin Private Message Manager above link. The original author is inactive to update it. I believe you can probably add more to the mod. Ask for his permission to take over and do something with it.
Personally I like modders to take over mods instead of making a new one out of scratch which is so time consuming. So I encourage you to build an excellent mod out of a foundation that someone has already. Building phpBB is a team work so that is why it is open source.