what do you mean, PM All Threads? like you send private messages to a user with all the threads? hmmm i hope thats not it... or did you mean PM All users? if so that hack already exist. If not, please elaborate.
he means PM all users that participate in a thread...
like a feature we have here, to send an update of the hacks when we click "install" - the coder can send a email to all user that have clicked install...