There are quite a few similar modules in the market.
Some only with birthday reminders, some only with inactivity reminders, and others only with not logged in within xx days reminder.
AntonLV's Automailer mod has it all!!! All the features, all the configurable settings and best of all, super great support!!! (i've worked with several vendors and AntonLV's support is really the most helpful, fastest, and comprehensive...simply the best!)
100% must buy!!