Blocklist
A blocklist is a list of domains, IPs, or addresses considered bad (spam, abuse, malware) and often blocked by filters.
Email & DNS~1 min read
In plain English
A list of “bad” domains or senders that mail and security systems use to block or filter spam and abuse. Being on a blocklist can hurt deliverability.
Blocklists (formerly often called blacklists) are maintained by various organizations and list IPs or domains known for spam, malware, or abuse. Mail servers and security tools check against them to reject or quarantine messages.
If your domain or IP is listed, email may be blocked or marked as spam. Keeping good sending practices and validating addresses helps avoid being listed.