I'm wanting to do something similar (but not quite the same!

)
I've just set up a new forum, and to encourage people to use it I wanted to send a notification to all users when a new thread is posted.
I'd leave this in place just until it starts to take off a bit - it's one of these niche forums for staff in a specific sector so doesn't have the draw of, say, a gaming forum or the like.
I've got people registering, I just want to use the notification to encourage people to visit the site regularly until it becomes a habit for them.
Any ideas if it could be done?