Mailshell SpamCatcher checks between 1,000 and 100,000 rules per message to accurately detect spam. Automatically updates new rules from the Mailshell SpamLabs. User can train SpamCatcher to learn what is and what is not spam. The system works with almost all POP e-mail clients and allows you to check your Hotmail/MSN account from any POP mail client. The core SpamCatcher Engine is also available for licensing into third-party products. Customized approved / blocked lists allow users to personalize filtering and caught spam is quarantined in a special 'SpamCatcher' folder right in their e-mail client. Combined with the separate Mailshell Web service, AOL, Hotmail, Yahoo!, and IMAP e-mail accounts are also supported. Combined with the separate SpamCatcher for Outlook, additional features are integrated into Outlook 2000 and Outlook 2002. Version 2.1 includes many new accuracy improvements and new Hotmail/MSN support.