Domain DNS Blacklist

What is a Domain DNS Blacklist?

A DNSBL, or a domain name server – based blacklist, DNS block list or domain blacklist is a list of IP addresses referenced by DNS server software to check if an email sender is a known spammer. Most mail servers will check DNSBLs to see if the sender’s domain name is associated with spammers, and occasionally if any of the links contained in the email are spam links. While DNSBLs can be a powerful tool for stemming the flow of spam, there are occasional false positives that result in legitimate email being flagged as spam and rejected by mail servers. The domain blacklist lookup tool lets you input a domain to see if it’s listed on any domain blacklists. This tool checks a number of the most commonly referenced DSBLs to see if the domain has been marked as a source of spam. This checks the host address against domain DNSBLs and also resolves DNS MX and A records and checks them against IP-based DNSBLs.

There are a number of reasons you may be included on a DNBSL, even if you’re not a spammer. For example, if your email account was hacked, or if your computer was exploited by a spammer virus, your IP address could be added to a DNSBL. This can prevent you from using your home computer or a personal web server from sending email.

Also, “spam – support operations” are also included in some DNSBLs. Spam support operations are sites that don’t directly send spam, but may provide services to spammers, such as web hosting. This can be problematic if spammers share the same web server (and thus the same IP address) as legitimate users. It’s possible that IP addresses and domains that are common to the spammer’s web server can also be improperly marked as spam.

If the domain blacklist check determines that you’ve been listed on any of the major DNSBLs, you can usually get yourself removed by contacting the DNSBL operator. Sometimes, this is a simple as filling out a form or sending a request. Other times, you may have to pay a fee, or meet certain criteria to prove that you are not a spammer.

At any rate, it’s helpful to know if you are listed on any blacklists. While not all mail servers filter according to all DNSBLs, it can explain why some of your emails are not reaching recipients.

Domain DNS Blacklist