I recently found this free email service, which I can't find any mention of here.
http://pubbox.net/
I think it's probably someone's hobby project, and I can't comment on reliability, but it looks pretty good.
- 1GB IMAP account
- SMTP server, which relays for any sender address
- Minimalist Squirrelmail webmail
- No ads on site or taglines on mail.
- 100MB FTP storage
- Very good spam filtering
It's the spam filtering that makes it particularly interesting. It's using a custom two-stage Bayesian filter based on Bogofilter. Anything that gets through Bogofilter, and has image attachements is sent through OCR and is tested again by Bogofilter. It seems to be very effective.