I hadn't even thought of a RBL. I guess I could create a script to IMAP in and check addresses and then move stuff around to SPAM folders if they meet an RBL criteria.
Downsides:
- RBLs could get legitimate mail as well and she'd have to check them again once they'd been sorted. The administration would be somewhat out of her hands then. Though, I guess I could build in some sort of override mechanism if I went this route.
- We use Exchange as the primary delivery method. Though we have POP and IMAP access, most people leave email up all day (you have to with Outlook's notify mechnism). I'd have to hit the server an awful lot to beat the "always on" nature of our Outlook setup. I don't think that would go over too well.
The Proxy idea appealed (in a completely theoretical idea) because it would be "always on". You could also build more tools into it in the future (worm blocking and stuff like that... if I got ambitious).
Something to think about.