How to Check If Your Domain or IP Is Blacklisted

The quickest way to find out whether your domain or sending IP is blacklisted is to run it through a checker that queries many blocklists at once, then confirm anything alarming with a direct DNS lookup. Both approaches read the same underlying data; the difference is convenience. Below are three methods, ordered from easiest to most hands-on, plus a table of what to test and where. Why this matters in the first place is covered in domain reputation explained.

A listing rarely appears at random. It usually follows a compromised mailbox, a misconfigured server that relays spam, or an IP whose previous owner misbehaved. Knowing which list flagged you, and why, is the first step toward fixing it, and it ties directly into domain reputation explained, where deliverability and trust are scored together.

Method 1: Use the free DomainIntel reputation tool

The simplest option is the free reputation checker at DomainIntel. Enter a domain and it queries the major blocklists in parallel, including the widely used Spamhaus zones, then returns a single summary of which lists flag you and which do not. You get the whole picture in one pass instead of testing each zone by hand, and there is nothing to install. For most people troubleshooting an email or reputation problem, this is the place to start.

Method 2: Run a manual DNS query

If you want to verify a specific list yourself, you can replicate exactly what a mail server does. The query format is documented in RFC 5782. Take your sending IPv4 address, reverse the four octets, and append the blocklist zone, then ask for an A record.

For the address 198.51.100.22 checked against a zone named bl.example.org, the lookup becomes:

dig +short 22.100.51.198.bl.example.org A

Read the answer like this:

• An answer in the 127.0.0.0/8 range means the IP is listed. The final octet is a coded reason set by the operator.
• An empty answer (NXDOMAIN) means the IP is not on that list.
• A follow-up TXT query on the same name returns a human-readable reason or a link.

Domain-based lists work the same way, except you query the domain itself rather than a reversed IP. Manual checks are precise but slow, since you repeat them once per zone.

Method 3: Use an operator's lookup page

Most blocklist operators host their own lookup tool. Spamhaus, for example, lets you check an IP or domain against its zones directly through its site, and the result page links to the specific reason and the delisting process. Operator pages are authoritative for that one list and are the right place to go once a multi-list checker tells you which operator flagged you.

What to check, and where

Domains and IPs are listed on different kinds of zones, so test both. Use this as a quick map:

What you are checking	Where to look	What a hit means
Sending mail server IP	IP DNSBLs (e.g. Spamhaus zones)	The server's outbound mail may be rejected or junked
Sender or link domain	Domain blocklists (DBLs)	Messages referencing the domain get filtered
Whole hosting range	IP DNSBLs covering CIDR blocks	A noisy neighbor on shared infrastructure may be the cause
Reputation summary	DomainIntel reputation checker at /	A combined view across many lists at once

If you are unsure what these lists actually are or how the query mechanics work, read what is a DNSBL. Found a listing? Your next move is how to get delisted from a blocklist, which walks through fixing the root cause before you ask an operator to remove you.

Want a clear answer right now? Check any domain's reputation free at DomainIntel and see its blocklist status across the major lists in one scan.