The Spamhaus IP-based DNSBLs contain real time data on IP addresses that have been observed to be involved in sending or hosting spam, including hijacked servers and computers infected with botnets.

Our IP blocklists include the Spamhaus Blocklist (SBL), the eXploits Blocklist (XBL), the Policy Blocklist (PBL), and the Auth Blocklist (Auth BL).

These listings are compiled using a wide range of investigative techniques including machine learning, heuristics and manual investigations. They analyze 9 billion SMTP connections daily.

This form of email filtering is an effective mechanism for removing the vast majority of junk email at the gateway. Secondary filtering, using more expensive anti-spam resources, can then be used to identify unwanted emails that manage to get through this first layer of defense.

The SBL, XBL and PBL can all be queried at the same time through Spamhaus “ZEN”. ZEN combines all three blocklists to speed up query times.

All our IP blocklists are included in a single subscription.

SBL

Spamhaus Blocklist

This list contains IP addresses that are observed to be involved in sending spam, snowshoe spamming, botnet command and controllers (C&Cs), bulletproof hosting companies and hijacked IP space.

A subset of the Spamhaus Block List (SBL) is the Botnet Controller List (BCL) which is an advisory “drop all traffic” list consisting of single IPv4 addresses, used by cybercriminals to control infected computers (bots). The BCL does not contain any subnets or CIDR prefixes larger than /32.

 

The SBL can be used as both a sender IP blocklist and a URI blocklist, to help protect your mailstreams from spam and botnet malware.

Senders whose IP addresses have been listed in the SBL will receive a bounceback message, allowing them to check the email addresses of recipients, or correct any other sending issues.

This blocklist is included in ZEN which combines the listings contained in the SBL, XBL, and PBL. This makes it easier and faster to query, and is available via our Data Query Service (DQS). For further information on consuming our blocklists via API, please contact us.

XBL

eXploits Blocklist

This lists the individual IPs (/32s) that are infected with malware, worms, and Trojans; third party exploits, such as open proxies; or devices controlled by botnets. The constantly updated list is designed to protect networks from malware and spam by preventing mailservers  from accepting connections from compromised computing devices.

The XBL only lists IP addresses of computing devices that attempt to send malicious spam. IP addresses that are not used to send email will not be included in the XBL, even if they are involved in other malicious activity.

 

The XBL is also available in an “enhanced” version (eXBL) which gives additional information for each individual IPs listing.

This blocklist is included in ZEN which combines the listings contained in the SBL, XBL, and PBL. This makes it easier and faster to query, and is available via our Data Query Service (DQS). For further information on consuming our blocklists via API, please contact us.

PBL

Policy Blocklist

The Policy Blocklist (PBL) includes IP address ranges for end-user devices, such as home routers, smart TVs, and other Information of Things (IoT) devices, from which email should never be sent.  This protects networks from the potential of being compromised by malware spread by botnet command and controller servers (C&Cs).

This list covers the majority of end user IPv4 space, in addition to some IPv6 ranges. While some individual IP addresses are included, most PBL listings are in classless inter domain routing (CIDR) format and are at least /24 in size.

 

By managing your own IP address range on the PBL, your organization can protect other networks from receiving spam from infected devices on your network. This helps to protect email recipients from malware, preserves the reputation of your company and avoids your domain being added to a DNSBL, which would result in your organization’s outgoing emails being blocked. To register your IP ranges, visit the Spamhaus PBL page.

This blocklist is included in ZEN which combines the listings contained in the SBL, XBL, and PBL. This makes it easier and faster to query, and is available via our Data Query Service (DQS). For further information on consuming our blocklists via API, please contact us.

Auth BL

Auth Blocklist

This is a subset of the XBL.  It lists IP addresses known to host bots using brute force or stolen SMTP-AUTH credentials to send spam, phishing and malware emails.

Botnets are often employed by cybercriminals to circumvent SMTP Auth: the security protocol that requires client machines to identify themselves to mailservers prior to being able to send or receive email.

 

We make the Auth Blocklist (Auth BL) available seperately, so you can use it at SMTP Auth as a score to make sure that someone isn’t trying to misuse a user’s account.

This subset is included in our IP blocklist subscription, and is available via our Data Query Service (DQS). It can also be consumed via an API.  For further information, please contact us.