SMTP Firewall:
XWall protects thousands of Internet exposed servers worldwide.

Offers spam analysis and blocked message retrieval.


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Spamhaus, Spamcop and other SLS...

A SLS service like....
Spamhaus, Spamcop, CBL and are DNS based blacklists. All these services have one thing in common. The use the DNS schema to give a heads-up or block result. This is a very efficient method and conserves bandwidth. It also can pass through most firewalls.

Spamhaus- Working to protect...
INTERNET NETWORKS WORLDWIDE Spamhaus tracks the Internet's Spammers, Spam Gangs and Spam Services, provides dependable real-time anti-spam protection for Internet networks, and works with Law Enforcement to identify and pursue spammers worldwide. (Source"

Spamhaus offers different services. The SBL service actively crawls the web looking for open relays and maintains a database of known spammers.

The XBL Spamhaus service is a list of exploits = worms, viruses and trojans. The XBL incorporates data from two highly-trusted DNSBL providers. The main suppliers are

  • the CBL (Composite Block List) from
  • the NJABL Open Proxy IPs list from

We recommend to use the Spamhaus This list combines the services and saves you bandwidth.

The latest Spamhaus list is ZEN. It includes dynamic addresses. It's generally assumed that mail servers have static addresses. It makes sense because "real" mail operations want to send and receive embalm. The Spammers on the other side just want to send. So it does not matter to them if the address changes. We recommend the ZEN service but make sure you do not check the message header for ip addresses. The header may contain dynamic IP addresses from the senders DLS connection going to the ISP's mail server.

Remember its spamhaus - not spamhouse


Spamcop ...
SpamCop determines the origin of unwanted email and reports it to the relevant Internet service providers. By reporting spam, you have a positive impact on the problem. Reporting unsolicited email also helps feed spam filtering systems, including, but not limited to, SpamCop's own service. Source:

Spamcop is a long time spam blacklist service. It is well balanced and has few false positives. Spamcop gets it's list by crawling the Internet and from users that report spam.

Composite Block List - CBL...
Most use CBL without even knowing. Spamhaus has integrated it in it's XBL list. Unlike other backlists CBL does not crawl the web. Instead it monitors many mailboxes that do not belong to real users. If one sends a message to these addresses it will blacklist the sender. This is very effective to catch spammers and specially zombie machines.

I had a few clients that ended up on the list due to virue infected machines in their office. CBL was very fast adding them and just as fast removing them once the problem was under control.

How does XWall use the blacklists

XWall can use one, two or as many blacklists as you like. It also can use them in groups. This is helpful if you want to minimize false positives. In that case the offender would have to be listed on multiple services before XWall declares the message spa,. Example: if you enter, and the sender is listed on both Spamhaus and Spamcop XWall will block the message.

XWall not only uses DNS blacklists it also can use Domain based black lists and the very popular SURBL. XWall can also use DNS While lists to exclude known mass mailers that do not mail spam. Click here to see more XWall features..