Deliverability
Blacklist
A database of IP addresses or domains identified as sources of spam. Also called blocklist or DNSBL.
Definition
A blacklist (also called blocklist or DNSBL) is a real-time database of IP addresses and domains identified as sources of spam or malicious activity. Email servers query these lists to decide whether to accept, reject, or filter incoming messages. Being listed on a major blacklist can severely impact email deliverability. There are over 100 blacklists, but only a handful (Spamhaus, Barracuda, SORBS) significantly affect deliverability.
Examples
Spamhaus SBL - lists known spam sourcesSpamcop - lists IPs reported by spam trap hits
Pro Tip
Monitor your sending IPs regularly using Kawaa's blacklist monitoring feature to catch listings early.