What is a domain blacklist?

A domain blacklist (DBL, URIBL, SURBL, RHSBL) is a list of domains flagged as sources of spam, phishing, malware, or other abuse. Mail servers check the sender domain and any link domains in the message body against these lists to decide whether to accept or filter the message.

How is this different from an IP blacklist checker?

IP blacklists target the sending IP address. Domain blacklists target the domain itself (in the From address) or domains that appear in the message body. This tool checks both — the domain on URIBL/SURBL/DBL, and each MX server IP on Spamhaus, Barracuda, SpamCop, and other IP-based DNSBLs.

URIBL is a "URI Block List" — a list of domains found in spam messages. Mail servers extract URLs from incoming messages and check the link domains against URIBL. A listed domain causes the message to be flagged regardless of who sent it.

SURBL is the Spam URI Realtime Block List. Operates the same way as URIBL — domains that appear in spam emails get listed, and receivers check link domains against the list. SURBL.org publishes multiple sub-zones for different categories of spam.

What is Spamhaus DBL?

The Spamhaus Domain Block List. Lists domains used to host spammer websites, phishing pages, malware, or botnet infrastructure. Influential — used directly or indirectly by Gmail, Microsoft, and most major email filters. A DBL listing is a serious deliverability problem.

My domain is clean but mail still gets blocked. Why?

Several possibilities: your sending IP (not the domain) is listed; SPF, DKIM, or DMARC is missing or broken; your domain reputation is poor at one specific receiver (Gmail or Microsoft tracks reputation separately); a link in your message body points to a listed third-party domain. Run the Email Deliverability Checker to confirm authentication is in place.

Can my domain be listed because of links I include in my emails?

Yes. URIBL and SURBL list any domain found in spam, including ones quoted, linked, or referenced in the message body. If you include a tracking link, an affiliate URL, or a third-party domain in your mail and that domain gets listed, your messages get caught too. Audit your link contents periodically.

I am on shared hosting and my IP is blacklisted because of another customer. What do I do?

Contact the hosting provider and ask them to delist the IP or, more likely, move you to a different IP. Long term, separate your sending infrastructure from shared hosting — an ESP like Mailgun, SendGrid, or Postmark costs a few dollars a month and gives you predictable sending reputation.

How do I delist my domain?

Each blacklist has its own removal process. Spamhaus DBL: removal at spamhaus.org/lookup. URIBL: contact form at uribl.com. SURBL: removal at surbl.org/removal. The cardinal rule: fix the root cause before requesting delisting, or you will be relisted within days.

How long does domain delisting take?

Varies by list. Spamhaus DBL: hours to a day after manual review. URIBL: 24-48 hours typically. SURBL: similar. Plan for at least 48 hours before delivery normalises everywhere. Some smaller lists are slower.

Free Domain Blacklist Checker — URIBL + SURBL + IP DNSBLs

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