We do infact have a mass emailing system in the forums. - I admit we haven't used it, for the fact that we never really thought about it. That, and perhaps the lack of content to send out as a mass-email.
It hasn't been discussed on our end before, but figuring out a reasonable email to send to people (relevant, etc.) might be tricky.
Suggestions are always welcome. Can't promise we'll do any of them, but I can appreciate a good idea.
Ps: I just glanced at the mailing module now - I think it's broken. MyBB is spitting errors at me. Shouldn't be terrible to fix though.. If required.
