WPBL - Weighted Private Block List - WPBL is a private block list consisting of IP addresses which connected to members' systems and delivered unsolicited bulk mail (spam). The list is designed to be useful and effective when used by WPBL members, but may not be suitable for other uses. This is NOT a public spam blocking service. WPBL should not be used to block mail or deny SMTP connections. It is most effective in a scoring-based system like SpamTestBuddy or SpamAssassin rather than black-and-white filtering.