Walter Mossberg recommends Mailblocks for a spam-free mailbox:
Mailblocks is a Web-based e-mail service, like Yahoo Mail or Hotmail, that works on both Windows and Macintosh computers. But it is slicker and cleaner than Yahoo or Hotmail, with a very good, uncluttered interface that responds to commands quickly. If you’d rather use a traditional e-mail program, you can read Mailblocks e-mail using Outlook, Outlook Express or Eudora on Windows, or Apple Mail or Entourage on the Macintosh.
You can divert e-mail from up to 10 of your current e-mail accounts to Mailblocks, and Mailblocks will apply its antispam system to all, including popular services like EarthLink, AOL, MSN, Yahoo Mail and Hotmail. You can also import address books from Outlook or Outlook Express and other programs, though you may have to go through several steps to do so.
Mailblocks uses a spam-control system called challenge/response. It’s designed to stop all e-mail from the automated mass-mailing programs spammers use, while letting in e-mail from humans. Mailblocks isn’t the first program to use challenge/response, but it does a very nice job with it.
There are some downsides. It doesn’t scan e-mail attachments for viruses. It lacks a “preview pane,” so you can see what’s in a message without opening it. It can’t auto-complete e-mail addresses you start to type in. And there’s no easy way to designate an entire domain — a whole company, for instance — as immune from challenges. The company says it plans to remedy some of these shortcomings in a new release due this summer that will also include a calendar function.
Overall, Mailblocks is a very good system for eliminating spam. And it will only get better.