What is blacklist?
Blacklist is a list of IPs suspected of sending spam. DNSBL (DNS-Based Blackhole List) and RBL (Real-time Blackhole List) list these IPs. They are used to prevent the transmission of spam to recipients. ISPs are using this information to determine if your mail will be accepted or not. Almost anyone can create a blacklist and there are a lot of them out there, you can see that through the Multirbl lookup tool.
Monitored blacklists
With so many blacklists out there, not all are considered equal by ISP's In order to determine which of them matter, we’ve put together a list of blacklist worth paying attention to:
Elastic Email actively monitors blacklists (including, but not limited to the ones listed) and if one of our servers ends up on one of them, our Delivery Experts investigate the issue and get us removed as quickly as possible. Furthermore, if we establish that such a blacklist could have a lot of impact on major ISPs we will add it to the list for future reference.
How can I get blacklisted?
All blacklist providers use a variety of ways to measure whether or not mail is wanted or unsolicited, but most include using some combination of spam traps and feedback loops.
Spam traps are fake or old email addresses that have been re-purposed to see if anyone sends emails to them. If they do, then the owners of those spam trap addresses know that the domain or IP sending mail to that address is sending unsolicited mail.
Feedback loops are another way that you can end up blacklisted. If there are too many direct abuse complaints (people mark your mail as spam or use other channels to report unwanted mail) then blacklist providers suspect unwanted mail and domains or IPs associated with that mail, and sometimes even mail that looks similar in nature.
How to resolve being blacklisted.
If you would like to know if you got blacklisted and what you can do about it you can use the guide we created specifically for this situation.
Furthermore, to ensure that you will not land in the blacklist again, follow our simple steps:
Don't send unwanted mail.
Don't send mail to email addresses that have not explicitly given you permission to mail them.
Don't purchase data or lists.
Use double opt-in subscription methods.
Keep your lists up to date.