For those still uncertain about blocking technologies, an easy entrance to the anti-spam scene comes in the form of Spam Interceptor, which is sold for the whopping price of nothing. The basic solution is free, while a more powerful upgrade is available that costs only $9.99 per year.
Unlike other software-based spam filters, which are installed onto the user's system, Spam Interceptor is a web-based program. Users route their incoming mail through Spam Interceptor's servers, where it is scrubbed clean. A bonus here is that a browser interface allows users to check their email from any computer. Your Spam Interceptor-filtered email is protected via SSL encryption.
With the free account users can store up to 10MB of email, plus attachments up to 3MB in size. A full Spam Interceptor account can store up to 50MB plus attachments up to 20MB in size.
The same downside with Cloudmark SpamNet also applies to Spam Interceptor — if the Spam Interceptor server goes down, you'll be unable to access your mail.
Spam Interceptor uses a mix of filtering technologies to fight spam. Its E-Mail Authentication Service ensures your email was sent by a real person. The first time someone emails you, they are asked a very simple question that only a human can answer.
Once they reply, they can send subsequent emails without ever having authenticate again. Users can also create a white list of trusted correspondents as well as a blocked list of those whose emails are to be forever rejected.