With the exception of SpamSlam, every antispam tool available for personal computers can be placed into one of three categories: a rule-based, challenge/response, or statistical filter. Each is effective in combating spam, but only SpamSlam combines the strengths of each. SpamSlam does not issue challenges to messages that are clearly legitimate e-mail or spam, greatly reducing the amount of bandwidth consumed by unnecessary challenge e-mails. SpamSlam's AccuFilter automatically trains itself, unlike other statistical filters, which necessarily require time and effort to train. These tools make SpamSlam a versatile antispam tool available for any POP3 client, including Microsoft Outlook and Express.

Version 2.1 brings greatly improved functionality.