XF 1.1 Auto send emails to users that have been registered for so long?

I'm wondering if it's possible to automatically send users emails or private forum messages when they've been registered on the forums for 1 week, 1 month and 3 months?

I'm running a Minecraft server and would like Xenforo to send users a password that they can use in-game to promote themselves, but only after they've been registered for certain periods of time.