Considering not using Google for hosting my mail. I could host my own server, but don't want to manage my own spam filters (unless tools are better than they were 5 years ago?). Alternatives? Would love a web mail solution, but it does not <i>have</i> to have that.
This has definitely been posted before and I still suggest <a href="http://www.fastmail.fm" rel="nofollow">http://www.fastmail.fm</a>. They've been around for a while and are always upgrading and updating their services.<p>If you want something enterprise-y, I'd suggest Rackspace either hosted Exchange or their IMAP solution (less expensive).
i use postini for spam filtering for my company and my hosted e-mail customers. postini acts as a proxy (you set them as your MX records, they forward legitimate mail to your SMTP server, and users can view their quarantined queues on postini's website). unfortunately, they were bought by google some years back and the false-positive rates for even medium-level filtering have gone up quite a bit, so you have to constantly check your quarantine looking for legitimate mail. i wish there were more choices in the outsourced spam filtering market.