I tried out free email hosting via Google Apps recently. The steps to do so are:
Create a Google Apps account.
Follow instructions to change MX records for your domain (via CPanel).
Follow instructions to change custom webmail URL (via support ticket with web host - CPanel doesn't support this).
Log into each webmail account and enable POP or IMAP access.
Follow instructions to configure your mail client (e.g. Outlook Express)
- You login to pop.gmail.com:995 as firstname.lastname@example.org
I think this will provide good spam filtering for free - and might therefore be useful for nonprofits and small businesses who don't want to purchase Outlook 2003 for their users. Outlook 2003 has an excellent built-in spam filter, updated monthly by Microsoft via Microsoft Update.