Blacklist Checker
Check a domain or IP against email blacklists.
Enter a domain or IPv4 address to check it against well-known email blacklists. We resolve the sending IPs and query each list live. A listing can quietly send your mail to spam, so it pays to catch one early.
The Blacklist Checker queries a domain or IP address against well-known DNS-based blocklists (DNSBLs) used by mailbox providers and spam filters. These lists, such as Spamhaus, SpamCop, Barracuda and others, record addresses associated with spam, malware, open relays or poor sending reputation. If your sending IP or domain is listed, receiving servers may reject, defer or junk your mail, so a clean result is an important part of healthy deliverability.
How a listing happens
An IP can be listed because of a spam complaint spike, a compromised account, a misconfigured mail server, sending to spam traps, or simply inheriting a bad reputation from a shared or recently reassigned address. Domain-based listings (and URI blocklists like the SURBL/URIBL families) flag the domains that appear in message bodies, which can affect you even when your sending IP is clean.
How to read the result and get delisted
A listing tells you which blocklist flagged the address; each list publishes its own reason and removal process.
- Find the root cause first, whether a hijacked account, a leaky form, or malware, because delisting without fixing it leads straight back to the list.
- Follow the specific list's removal procedure; most offer a self-service delisting form once the issue is resolved.
- Check your authentication: valid SPF, DKIM and an enforced DMARC policy improve reputation and reduce future listings. See how to audit your setup.
- Warm up new IPs gradually and keep complaint rates low.
Reputation and authentication go hand in hand; our managed service keeps both under continuous watch for the domains we look after.
Frequently asked questions
What is a DNSBL?
A DNSBL (DNS-based blocklist), sometimes called an RBL, is a list of IP addresses or domains with poor sending reputation, published over DNS so that mail servers can query it in real time during message acceptance. If the queried address returns a listing, the receiving server may block, defer or junk the message.
Why is my IP listed when I haven't sent spam?
Common causes include a compromised mailbox or website form being abused to send mail, a shared or newly reassigned IP that inherited a previous tenant's bad reputation, hitting a spam-trap address, or a misconfigured server acting as an open relay. Identify and fix the source before requesting removal, or you will be relisted.
How do I get removed from a blacklist?
Each blocklist runs its own delisting process, usually a self-service form on the operator's website. First resolve the underlying problem, then submit the removal request. Some lists expire entries automatically after a clean period, while others require a manual request.
Does being blacklisted mean my DMARC or SPF is broken?
Not directly. Blocklists track reputation and abuse, not your authentication records. However, weak or missing SPF, DKIM and DMARC make it easier for others to spoof your domain and harm its reputation, which can lead to listings. Strong, enforced authentication supports a clean reputation. See our enforcement guide.
What is the difference between an IP blacklist and a domain (URI) blacklist?
An IP blocklist flags the address your mail server connects from, while a URI/domain blocklist (such as the URIBL or SURBL families) flags domains that appear in the message body or headers. You can pass IP checks but still be filtered if a domain you link to is listed, so it is worth checking both.
How often should I check?
For active sending infrastructure, check regularly. Weekly is reasonable, or check immediately if you notice a sudden drop in delivery or a rise in bounces. Continuous monitoring catches a listing early, before it does lasting damage to your reputation.