Blocklist Checker
Check whether a sending IP or domain is on the major email blocklists (DNSBLs) (Spamhaus, Barracuda, SpamCop and more) and get the delisting link for any list that has it. Free, no signup.
Email blacklist search for sending IPs and domains
An email blocklist (also called a DNSBL, RBL, or blacklist) is a list of IP addresses and domains that have been caught sending spam or abusive mail. Mailbox providers query these lists as messages arrive and use a listing as a reason to reject, defer, or spam-folder your email. Getting listed is one of the fastest ways to wreck deliverability, and because listings key off a sending IP’s reputation, a single compromised account or a bad mailing list can take down all of your mail at once. This checker tells you which lists currently have your IP so you know exactly where to request removal and what to fix first.
How to read your blocklist result
| Result | What it means | What to do |
|---|---|---|
| Listed | At least one queried blocklist returned a positive listing for the submitted address. | Confirm the exact list and resource, fix the compromise or sending practice that caused it, then use the operator's official delisting process. |
| Not listed | The blocklists successfully queried did not list the submitted resource at that moment. | Keep investigating authentication, private reputation, bounce details, and the actual sending IP; this is not an inbox guarantee. |
| Can't check | The operator did not return a reliable result to the resolver used by the hosted tool. | Treat the status as unknown and follow the operator link for a direct lookup rather than assuming the resource is clean. |
Check the resource that actually sent the message
Most email blocklists are IP-based. A domain lookup can resolve a website or other host that never sends mail, so it may answer the wrong question. Use a trusted message header or bounce to find the outbound IP evaluated by the receiver, and record the provider, timestamp, rejection code, and affected stream with the check.
Fix the cause before requesting removal
A listing can come from a compromised account, spam-trap hits, purchased lists, high complaints, poor list hygiene, missing reverse DNS, or another sender on a shared IP. Confirm who controls the address and stop the harmful traffic first. If the IP belongs to an email service provider, work through that provider rather than claiming the address yourself. Then use the list operator's official removal instructions and rerun the same IP check.
When the listed resource is a domain, pair the result with the domain reputation check. For a real-message diagnosis, use the email deliverability test so the outbound IP and authentication evidence come from the same path.
Related blocklist and reputation checks
Email blocklist knowledge base
What is a DNS blocklist (DNSBL)?
A DNS blocklist, or DNSBL, is a published list of IP addresses (and sometimes domains) that have been seen sending spam or abusive mail. Receiving mail servers query these lists in real time and use a listing as a signal to reject, defer, or spam-folder your message. They are also called RBLs (Realtime Blackhole Lists) or blacklists.
How do I check if my IP or domain is blocklisted?
Enter your sending IP address (or a domain, which we resolve to its IP) above and run the check. The tool queries several major blocklists at once and shows whether the address is listed on each, along with a delisting link for any list that has it. For the most accurate result, check the exact IP your mail actually leaves from: for most senders that is your email provider's or ESP's outbound IP, not your website's IP.
Why does the tool say it 'can't check' Spamhaus or Barracuda?
Several large operators, including Spamhaus and Barracuda, only answer blocklist queries that come from a dedicated, registered resolver. Queries from a large shared resolver (like the one a hosted app uses) are answered with an error code instead of a real result. When we detect that, we show 'Can't check' and link to the operator's own lookup page so you can confirm directly, rather than reporting a false 'not listed'.
How did my IP end up on a blocklist?
The most common causes are: spam or unsolicited mail sent from the IP (sometimes by a compromised account or device on the same network), hitting spamtraps from an old or purchased list, a poor sending reputation from high complaint or bounce rates, missing or generic reverse DNS (PTR), and shared-IP problems where another sender on the same address caused the listing. Fixing the root cause matters more than the delisting itself.
How do I get removed from a blocklist?
First fix what caused the listing: secure any compromised accounts, clean your list, and make sure your mail is authenticated with SPF, DKIM, and DMARC. Then use the operator's delisting form (linked next to each listing above). Many lists, such as SpamCop, expire entries automatically once the abuse stops, so patience plus a fixed root cause is often enough. Requesting delisting without fixing the cause almost always leads to a re-listing.
Does being on a blocklist always block my email?
Not always. Some lists are consulted by almost every receiver (Spamhaus is the most influential), while others are used by only a handful of servers or are purely advisory. A listing on a widely used list can cause outright rejections; a listing on a niche list may only nudge you toward the spam folder. The checker shows every list separately so you can judge the impact by which list has you.
Should I check the IP or the domain?
Most blocklists are IP-based, so the sending IP is what matters for delivery. If you enter a domain, we resolve it to an A record and check that IP, but note that is often your website's host, not the server that sends your email. To diagnose a delivery problem, look at your bounce message or email headers to find the real outbound IP and check that.
The terms behind DNS blocklists and how a listing works.
- DNSBLDNS blocklist
- A blocklist published over DNS. A receiving mail server checks a sending IP by querying the reversed IP under the list's zone; an answer means the IP is listed. Also called an RBL (Realtime Blackhole List) or blacklist.
- SBLSpamhaus Block List
- Spamhaus's list of IPs from which they do not recommend accepting email, based on evidence of spam operations. Part of the combined ZEN zone.
- XBLExploits Block List
- Spamhaus's list of hijacked machines, proxies, and malware-infected hosts. Being on the XBL usually means a device on your network is compromised, not that you sent spam deliberately.
- PBLPolicy Block List
- Spamhaus's list of IP ranges that should not be sending mail directly to the internet (e.g. residential/dynamic IPs). Sending from a PBL-listed IP means you should relay through your provider's mail server instead.
- listing
- The state of an IP or domain appearing on a blocklist. A listing returned by a lookup is typically an address in the 127.0.0.0/8 range, where the last octet encodes why it was listed.
- delisting
- Removing an IP or domain from a blocklist. Most operators offer a self-service removal form, but delisting only sticks if the underlying problem (spam, a compromised host, poor authentication) is fixed first.
- spamtrap
- An email address that never opts in and exists only to catch spam. Mail sent to a spamtrap is strong evidence of a bad list or scraped addresses and is a common cause of a listing.
- snowshoe
- Spreading spam thinly across many IPs and domains to stay under per-source volume limits. Blocklists specifically hunt for snowshoe patterns.
- PTRReverse DNS
- The PTR record maps a sending IP back to a hostname. A missing or generic PTR record makes an IP look untrustworthy and contributes to listings and filtering.
- 127.0.0.xReturn code
- The A-record value a DNSBL returns for a listed IP. Different last octets mean different sub-lists or reasons. A 127.255.255.x value is not a real listing. It signals the query was refused (often because it came from a large shared resolver).