email blacklist checker.
Resolve a client domain's mail infrastructure, check it against Spamhaus, SpamCop, and 20+ other blocklists, then return each listing reason and delisting link.
The blocklists that decide whether your mail gets through.
Mail servers consult DNS blocklists (DNSBLs) before accepting a message. We run those queries live against the mail infrastructure associated with the domain.
your mail server IPs
We look up the domain's MX records, resolve every mail host to its IP addresses, and test those addresses against IP blocklists.
major IP blocklists
Spamhaus ZEN (SBL, XBL, and PBL combined) and SpamCop, the lists large mailbox providers actually consult. A listing here usually means rejected or junked mail.
20+ additional lists
PSBL, Mailspike, DroneBL, UCEPROTECT, SpamRats, and more. Narrower adoption, but listings add up as negative signals in spam filtering.
domain blocklists
Your domain name itself is checked against Spamhaus DBL, SURBL, and URIBL — the reputation lists filters use to score the domains that appear in mail.
the listing reason
When a list answers, we decode the response code and fetch the TXT record explaining why, so you know what you're dealing with before you visit the delisting page.
honest unknowns
A blocklist that times out or refuses the query is reported as unchecked, never as listed. You only act on answers the list actually gave.
A blacklisted server fails silently.
mail vanishes without errors
Receiving servers that trust a blocklist reject or junk your mail at the door. Senders see no bounce half the time — messages just stop arriving and nobody tells you.
one incident is enough
A compromised mailbox, a misconfigured form, or a burst of complaints can land your IP on a list within hours. The listing outlives the incident until someone requests removal.
shared infrastructure spreads risk
On shared hosting or a neighbor-heavy IP range, someone else's spam can put your address on network-wide lists like UCEPROTECT even when your own sending is clean.
delisting starts with knowing
Every reputable blocklist has a removal process, but it only starts when you find the listing. Most teams discover a blacklisted IP weeks late, from a customer asking where the invoice went.
Email blacklist questions, answered.
A DNS-based blocklist (DNSBL, also called an RBL) is a published list of IP addresses or domains observed sending spam or hosting abuse. Mail servers query these lists over DNS in real time when a message arrives and use the answer to reject, quarantine, or score the message. Spamhaus and SpamCop are the best-known examples.
We look up your domain's MX records, resolve each mail host to its IP addresses, and query each IP against 20+ IP blocklists using the standard DNSBL mechanism: the IP's octets are reversed and prepended to the list's zone, and an answer in 127.0.0.0/8 means listed. The domain itself is checked the same way against domain blocklists like Spamhaus DBL and SURBL.
First, fix the cause — a compromised account, an open relay, a form being abused to send mail, or missing authentication. Then request removal through the blocklist's delisting page (we link each one). Delisting without fixing the cause just gets you relisted, and some lists penalize repeat offenders with longer listings.
It depends on the list. A Spamhaus or SpamCop listing means major providers are likely rejecting or junking your mail right now. Smaller lists are consulted by fewer servers and mostly add negative score rather than block outright. UCEPROTECT Levels 2 and 3 list entire networks, so a listing there often reflects your hosting provider's neighborhood rather than your server.
A blocklist zone can time out, be discontinued, or refuse queries it can't attribute — Spamhaus, for example, refuses queries arriving through large public resolvers. When that happens we report the list as unchecked rather than guessing. An unchecked list says nothing about whether you're listed on it.
Check after any deliverability dip, after a security incident, and before warming up a new sending IP or domain. For ongoing coverage, continuous monitoring beats manual checks — listings appear at random times and the damage accumulates until you notice.
A blacklist result is one part of the client domain.
The free scan checks blacklists, email auth & DMARC, SSL & domain expiry, and look-alikes together from public records. One result, no signup.
Keep checking the same failure point.
Use the related tools one at a time, or run all four posture checks together.