Request: Timed automailer by activity

I don't know how to request a plug in for consideration, but I've been thinking a lot about the type of functionality that would be great to encourage community engagement over time. While we use the auto-message, it would be better if I could set the following types of parameters:

send message X (e.g. "Hey, you haven't posted in a while.")
if user hasn't posted in X days (e.g. only email members who don't post within 25 days)
and they've been a member for X days (e.g. only email members for first two years after joining)

If there is a way to do this, would definitely love for someone to point me to it. Otherwise, I'd love to see this get built.