Blacklist: A Blacklist is made up of mail servers (IPs) or domains (Brands) that were identified as a sender of spam. Some blacklists are compiled automatically, while others are put together by individuals. The blacklist community range from respected protectors of the space (Used at major ISPs) to small operations with only a few members managing it (Not often used). Both blacklists can be arbitrary applied, and often rule in ‘False Positives’ (Corporate Firewalls are often the biggest abuser here).
Due to a large number of Blacklists (200), it’s Revinate’s policy that we recommend that customers only take action on the following blacklist providers -
SpamCop - SpamCop lists spam sources based on reports from users of the SpamCop reporting system. SpamCop attempts to estimate the level of spam/legitimate traffic from each address reported. SpamCop is highly aggressive, and their processes result in numerous false positives, typically legitimate list traffic running COI (confirmed opt-in). Because of this, SpamCop is not widely used at major ISPs, and a listing does not have a large impact on the average mailing list.
SORBS - The Spam and Open Relay Blocking System (SORBS) was started in 2002 and lists servers that have been compromised. Over the years SORBS has expanded over time to include hacked and hijacked servers, farmmail scripts, trojan infestations (particularly those with backdoors), and has more recently made the move to preemptively list blocks of dynamically allocated IP address space. More information is available at http://www.us.sorbs.net/faq/
Spamhaus - The Spamhaus Project operates lists which have the biggest deliverability impact on most senders. It runs the Spamhaus Block List (SBL) and the Exploits Block List (XBL), and maintains the Register of Known Spamming Operations (ROKSO). A team of volunteers located all over the world maintains the Spamhaus Project. The SBL is widely used and protects as many as 40 million mailboxes.
SBL: The SBL is a real-time database of IP addresses of verified spam sources (including spammers, spam gangs, and spam support services), maintained by the Spamhaus Project team and supplied as a free service to help email administrators better manage incoming email streams. This is one of the more respected blacklists and a listing on the SBL can significantly impact deliverability.
XBL: The XBL is a database of IP addresses of exploited machines. It is currently a mirror of the data from another blacklist (the Composite Block List (CBL) from http://cbl.abuseat.org). This list is a technical list designed to catch and stop infected or compromised servers from sending spam.
ROKSO: The Register of Known Spamming Operations lists hard-core spammers who have been kicked off 3 or more Internet Service Providers.
If a customer is ever listed on Spamhaus, it is Revinate’s Policy to temporarily suspend that account if it's listed on any one of the three Blacklists noted above. Revinate will then work with Spamhaus and the customer to correct the issue to avoid this from happening again.