UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? A way to expire watch lists?

I'd like to have the option to have a dedicated email for the forum to handle any bounce or response to a PM. I get a ton of random emails from my forum and it is tiring to have to go in and manually set people's setting to not receive emails on PMs. I'd love to see where if their email bounces it would make them revise their registration with a new email. If they respond to a PM it could add that response to the actual PM.