"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.
While WPBL detects a considerable amount of spam on a daily basis, the thresholds for getting listed are low. This is why we emphasize that you should not block mail purely because an IP address is on our list. If you are looking for a blocklist appropriate for mail rejection with few false positives, consider CBL or Spamhaus ZEN (includes CBL), which are two very high quality blocklists.
Mail servers that send us bounces/backscatter resulting from forged addresses will be listed as a spam source, since they are sending us unsolicited bulk e-mail. Hosts which send us more backscatter than legitimate mail will be listed along with other spam sources in the blocklist. When a spammer forges our address and your mail system automatically returns mail to the forged address, you are generating new spam and causing a problem for our members. If we are receiving such spams, then other innocent sites on the internet are as well. Some of our members receive thousands of these spams daily. Please check your mail system for this problem.