Blocklist (blacklist)
Also called: Blacklist, DNSBL, RBL
A blocklist is a published list of domains or IP addresses associated with spam, which mail servers and filters look up when deciding what to accept. Older material calls them blacklists.
Domain lists such as the Spamhaus Domain Blocklist (DBL) list domains with poor reputation, never IP addresses; listings expire once a domain no longer meets the criteria, and removal can be requested free of charge (Spamhaus). IP lists work the same way for sending servers.
How it affects cold email
A listing on a major list can send all your mail to spam or get it rejected, and a listed domain in a link can hurt an otherwise clean email. Listings usually follow spam trap hits, complaints or compromised accounts.
How Inboxed handles it
- Inboxed looks up each sending domain on Spamhaus DBL, SURBL and URIBL every 6 hours. A listing pauses every mailbox on that domain, with the reason, and is logged on the Activity page. A failed lookup never pauses anything. Big shared providers such as gmail.com are skipped, since a listing there wouldn’t be about you.
- Check any domain yourself with the free domain checker.
Related terms
Sources
Sources checked on 8 November 2026. Rules change, so check the source before you rely on a detail.
- Domain Blocklist FAQ · Spamhaus
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