If you send marketing emails you are more than likely familiar with the many blacklists in use today. One thing to keep in mind when you find yourself on one of these lists is that most lists will contain just about any email marketer at one point in time or another. At the end of the day, if you are sending promotional mail, you’ll need to pay attention to any listings that may arise, but must quantify taking action against any listing based on the impact to your own deliverability.
Any listing is indicative of a systemic issue: list hygiene. If you find yourself listed, you may simply be mailing promotional mail to your own subscriber base, mailing to an unengaged audience or not setting proper expectations with your customers. Most listings will have minimal impact on deliverability (outside of a Spamhaus listing), but all are a red flag and should be monitored regularly.
While we are constantly monitoring all of our sending domains and IP addresses to ensure that we may address any critical listings, the Cordial Deliverability Operations team recommends that you also regularly check any domains/IP addresses that you have in use against private and public blacklists.
Below are a few of the more common blacklist checkers available, as well as a list of the most common blacklists in use today.
|The Anti-Abuse Project||anti-abuse.org/multi-rbl-check|
|SORBS (Spam and Open Relay Blocking System)||sorbs.net|
|SBL (SpamHaus Blocklist)||spamhaus.org/sbl/|
|PBL (Spamhaus Policy Block List)||spamhaus.org/pbl/|
|CBL (Composite Blacklist), a division of Spamhaus||cbl.abuseat.org|
Top 3 Blacklist Owners That Cordial Monitors
The most common blacklist owners that the Deliverability Operations team may come across while monitoring here at Cordial are:
Spamhaus is the most highly visible blacklist owner active today and will impact one’s mailing capabilities greatly. 70-80% of all mail sent by those listed on a Spamhaus blacklist will be blocked by the ISP/MBPs who are utilizing these lists. A detailed outline of the various lists may be found below.
|SBL||Spamhaus Block List||IP Address||spamhaus.org/sbl|
|XBL||Exploits Block List||IP, exploited computers and other devices||spamhaus.org/xbl|
|PBL||Policy Block List||IP Address Ranges||spamhaus.org/pbl|
|DBL||Domain Block List||Domain||spamhaus.org/dbl|
|CBL||Composite Blocking List (a division of Spamhaus)||IP Address - Easy removal||abuseat.org|
SORBS is another commonly found blacklist owner and we have found that the impact to any mailing program is minimal, especially compared to a listing by Spamhaus.
The SORBS (Spam and Open Relay Blocking System) is a DNS-based Block List (DNSBL) that is reported by SORBS as a way for MBP/ISPs to disseminate spam, phishing attacks and other forms of malicious email. The list typically includes email servers suspected of sending or relaying spam, servers that have been hacked and hijacked, and those with Trojan infestations. In an attempt to provide preemptive protection, SORBS also lists servers with dynamically allocated IP addresses.
|SORBS||Spam and Open Relay Blocking System||DNS||sorbs.net|
SpamCop provides the SCBL and describes it as an aggressive spam-fighting tool. According to the SpamCop website, by using this list Mailbox Providers & Internet Service Providers are able to block spam, but legitimate/wanted mail may also become blocked in the process. Because of this limitation, SpamCop strongly suggests using the SCBL as part of a scoring system, along with whitelisting wanted email senders (e.g., mailing lists and other IPs from which you want to receive email).
|SpamCop||Aggressive spam-fighting tool||spamcop.net|
The SCBL is a list of IP addresses which have transmitted reported email to SpamCop users, which in turn is used to block and filter unwanted email. The SCBL is a fast and automatic list of sites sending reported mail, with a number of report sources, including automated reports and SpamCop user submissions. The SCBL also quickly and automatically delists these sites when reports stop.