If your emails have started bouncing, vanishing, or landing straight in the spam folder, there's a strong chance your domain or its sending IP has been blacklisted. Blacklists are one of the most common — and most overlooked — reasons legitimate email stops getting through. The good news is that checking whether you're listed takes just a couple of minutes with free tools, and getting removed is usually straightforward once you know the cause. Here's how to check if a domain is blacklisted and what to do about it.

What is a domain or IP blacklist?

A blacklist (technically a DNSBL — DNS-based Blocklist, sometimes called an RBL) is a database of domains and IP addresses that have been flagged for sending spam or malicious email. Mail servers around the world consult these lists in real time: when a message arrives, the receiving server checks whether the sender's IP or domain appears on a blacklist, and if it does, the message is blocked or dumped into spam before it ever reaches the inbox.

There are dozens of these lists, run by different organizations (Spamhaus is one of the best known). Landing on even one major list can tank your email deliverability.

Domain blacklist vs IP blacklist

There are two things that can get listed, and it helps to know which you're dealing with:

  • IP blacklists target the sending mail server's IP address. This is the most common type — if your server (or a server you share) sends spam, its IP gets listed.
  • Domain blacklists (URIBLs/SURBLs) target the domain name itself, often based on links appearing in spam messages.

To check either, you first need to know your sending mail server's IP. You can find the IP behind a hostname using the methods in our guide on how to find a website's IP address, and confirm your mail setup with our DNS Records tool (check your MX and A records).

How to check if you're blacklisted

You don't have to query dozens of lists one by one. Free online blacklist checkers exist that test your IP or domain against many DNSBLs at once and show you exactly which lists you appear on. To use one:

  1. Find your sending IP. Look up the IP of your mail server (the one in your MX/sending configuration).
  2. Run it through a free multi-blacklist checker. Enter the IP (and separately, your domain) and let it query the major lists simultaneously.
  3. Read the results. A clean result across the board means you're not listed. Any "listed" flags tell you exactly which blacklists to address.

It's worth checking both your IP and your domain, since they can be listed independently.

Why domains and IPs get blacklisted

Understanding the cause matters, because you'll need to fix it before requesting removal — otherwise you'll just get relisted. Common reasons include:

  • Sending spam (knowingly or not), or emailing stale, purchased, or unconsented lists.
  • A compromised account or server sending spam without your knowledge — a very common cause.
  • Malware or a hacked website sending mail from your domain.
  • Missing or broken email authentication. Without proper SPF, DKIM and DMARC records, your mail looks untrustworthy and is far more likely to be flagged.
  • A bad neighbor on shared hosting. If you share a mail server IP, another user's spam can get the whole IP listed.
  • Sudden sending spikes from a new IP that hasn't been "warmed up."

How to get delisted

Once you've confirmed a listing, here's the removal process:

  1. Fix the root cause first. Secure any compromised accounts, stop the spam source, clean your mailing lists, and set up proper authentication. Requesting removal before fixing the problem is pointless.
  2. Visit the specific blacklist's website. Each list (the checker tells you which ones flagged you) has its own delisting page. Follow their removal request process.
  3. Wait. Some lists remove you automatically after a period of clean behavior; others process manual requests within a day or two.

Be patient and thorough — jumping straight to delisting requests without fixing the underlying issue is the number-one reason domains bounce right back onto the lists.

How to avoid getting blacklisted

Prevention is far easier than removal:

  • Set up SPF, DKIM and DMARC so your mail is authenticated and trusted — the single most effective safeguard against being flagged.
  • Keep your lists clean. Only email people who opted in, and remove bounces and unsubscribes promptly.
  • Secure your accounts and website to prevent compromise.
  • Confirm your mail routing is correct with our MX records guide.
  • Monitor your reputation by checking your IP and domain against blacklists periodically, so you catch a listing early rather than after your deliverability collapses.

The bottom line

If your email isn't getting through, checking whether your domain or IP is blacklisted should be one of your first moves. Find your sending IP, run it and your domain through a free multi-blacklist checker, and see which lists (if any) flag you. Then fix the root cause — spam, a compromise, or missing authentication — before requesting removal. Pair that with solid SPF, DKIM and DMARC and good list hygiene, and you'll keep your domain off the blacklists and your email in the inbox where it belongs.