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Email Blacklist Check

Enter an IP or domain to check if it appears on 6+ major email blacklists.

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Server processing — checks 6 major DNSBL blacklists securely on our servers.

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Enter an IP address or domain and check it against major DNSBL blacklists.

How to use Email Blacklist Check

The Blacklist Check queries dozens of well-known DNS-based blocklists (DNSBLs) to see whether an IP address or domain has been flagged for sending spam or hosting abuse. If your mail server’s IP appears on a major blocklist, receiving servers may delay, junk or outright reject your messages, so a listing is a direct cause of email delivery failure. Use this tool when legitimate mail starts bouncing, before migrating to a new sending IP, or as a routine health check to catch a listing early while it is still easy to resolve.

  1. Enter the sending IP address or domain to test.
  2. Click Check to query the major DNSBL providers.
  3. Review which lists, if any, report a listing.
  4. Open each listing provider to read the reason and delisting steps.
  5. Fix the underlying issue, then request delisting and re-check.

How DNS blocklists work

A DNSBL is a list of IPs or domains known for abuse, published over DNS so mail servers can query it in milliseconds during a connection. When a sending IP matches an entry, the receiving server decides what to do — some reject outright, others lower the message’s reputation. Different lists have different policies and reputations; a listing on a strict, widely-trusted list like Spamhaus carries far more weight than one on an obscure list few servers consult. This tool checks many at once so you see the full picture.

Getting delisted and staying off

A listing is a symptom, so removing it without fixing the cause invites a swift relisting. Common causes include a compromised account sending spam, a misconfigured mail server acting as an open relay, or a shared IP poisoned by another user. Once the root cause is resolved, visit the listing provider’s site and follow its delisting request; reputable lists remove clean IPs quickly. Maintaining proper SPF, DKIM and DMARC, plus rate-limiting outbound mail, is the best way to avoid future listings.

Common listing causes
CauseFix
Compromised accountReset credentials, scan for malware
Open relayRestrict relaying to authenticated users
Poor list hygieneRemove bounces, honour unsubscribes

Glossary

DNSBL
A DNS-based blocklist of IPs or domains associated with abuse.
Spamhaus
One of the most widely trusted blocklist operators.
Open relay
A mail server that forwards mail for anyone, often abused by spammers.
Delisting
The process of having an address removed from a blocklist.
Sender reputation
A score mailbox providers assign to a sending IP or domain.

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