Concentric offers basic mail filtering for free, but you may want to consider upgrading to Premium mail filtering.

Standard Mail Filtering is fine for those with very basic email needs, but Premium Level would be a good choice if you get a lot of Junk Mail, are on many mailing lists, or have special mail handling needs.

After you’ve enabled Premium Mail Filtering you can customize additional Mail Handling Rules, modify delivery features and train a Premium Filter based on your e-mail to better protect your inbox.

The Premium Mail Filter relies upon individual user feedback for initial training and ongoing corrections. Think of it as a personal Junk Mail filter that you can train based on the email that your account receives. By showing the Junk Mail Filter what you do and don’t consider Junk Mail, this feature will tune the filter to more closely fit your specific emails. The better you train it, the more accurate it becomes.

You can upgrade to Premium Mail Filtering on the Email Settings page (linked from the Concentric Center). There is a small monthly charge per user for enabling Premium Mail Filtering, but many users find the service invaluable, especially if you’ve had your email address for a long time or you find that your email address has propagated itself around the spam lists. For further explanation, see the Junk Mail Filter FAQs.