IP Block Lists

50 billion spam messages will be sent each day!
Spamhaus will block 95% of them at connect time, without accepting any data.


When you trial the Spamhaus Block Lists for FREE for 30-days and install them on your network, you’ll see 95% of your inbound SPAM traffic being blocked. MXTools provides dependable real-time anti-spam data feeds to more than 1,500 customers worldwide. We keep networks safe, users secure and costs low.

Spamhaus tracks the Internet’s Spammers, Spam Gangs and Spam Services, providing dependable real-time anti-spam data feeds, one of which is the powerful and highly trusted IP reputation block list or DNSBL described here. It is universally supported by all major email platforms, and used globally by hundreds of large network operators, mobile carriers, universities, governments and companies of all sizes to protect over 2 billion mailboxes.

All Email servers must have a fixed IP address in order to send Email. This address can be used to determine if a mail server is responsible for sending Spam or other malicious content. Doing an IP Reputation lookup on a message at SMTP connect time is cheap in hardware cycles and system time.

If your Email server already knows the incoming message is coming from a spammy or otherwise mistrusted IP address, it can simply deny a message from entering the network, rather than having to accept the data and then pass it on to a mail-scanner, virus scanner, content filter or other network tests. A common mail flow with IP reputation is explained here.

“It is worth noting that those lists (Spamhaus Zen) didn’t have any false positives, yet still blocked more than nine out of ten spam emails based on the sending IP address alone.”

quote souceSource: Virus Bulletin VB Spam Benchmark results, March 2015.

DNSBL Technical specifications

The IP data feeds provided covers static and dynamic spam sources, IP addresses displaying infected and botnet behavior, and IP addresses that should never emit Email.

  • Separate data feeds for policy and compromised IP behavior.
  • Cloud query via DNS or local download (rsync) for large networks.
  • IPv4 and IPv6 supported.
  • Built with spam trap, honeypot and ISP production feedback data.
  • Network owners & ISPs publish their own policies for their IP space (PBL).
  • Updated every 5 minutes.

Full specifications and deployment/usage scenarios are covered in detail here

The Spamhaus IP Block Lists (SBL, XBL, PBL, Zen) will greatly decrease the amount of resources needed to accept, process and store bad email. Let us be your most effective first line of defense against Spam, by blocking over 90% of all bad mail at connection time, (closer to 95% when combined with the Spamhaus DBL) without ever accepting any harmful data.

Our block list will instantly eliminate spam, improve Email performance & lower your bandwidth & storage costs. Contact us today to start your free trial.