Blacklist Checker
Check whether a domain's mail server (or a specific IP) is listed on major email DNSBL blacklists (Spamhaus, Barracuda, SpamCop, SORBS). A listing can silently send your emails to spam.
What is a DNSBL blacklist?
A DNS-based Blacklist (DNSBL) is a list of IP addresses known to send spam, run open mail relays, or otherwise behave abnormally. Mail servers check incoming connections against these lists in real time — if your sending IP is listed, a meaningful share of your email may be silently rejected or sent straight to spam.
How domains end up listed
Usually not intentionally — shared hosting IPs can get listed because of another customer's compromised site, a misconfigured mail server can be exploited as an open relay, or a marketing tool sending too aggressively can trigger spam-trap hits that get an IP flagged.
What to do if you're listed
Each blacklist operator has its own delisting process, usually a short form on their site confirming the issue is fixed. Fix the underlying cause first (secure the server, stop the offending sender) before requesting removal, since re-listing after a rushed delisting is common.