Spamhaus Policy Block List
The Spamhaus PBL is a DNSBL database of end-user IP address ranges which should not be delivering unauthenticated SMTP email to any Internet mail server except those provided for specifically by an ISP for that customer’s use. The PBL helps networks enforce their Acceptable Use Policy for dynamic and non-MTA customer IP ranges. PBL IP address ranges are added and maintained by each network participating in the PBL project, working in conjunction with the Spamhaus PBL team, to help apply their outbound email policies.
The Spamhaus PBL lists IP addresses that have no reason to be delivering unauthenticated SMTP email to any host on the Internet. For example, most residential ISP’s that provide Internet access to end users, expressly forbid the user of their connections to be used for any “server” based activity. This includes, but it not limited to, SMTP servers. While some ISP’s have business class divisions of their internet access, the residential side of their offerings does not allow one to directly submit email from their dynamic IP connection.