Blacklist Checker
Check your domain and mail server IPs against 12 major DNS-based blacklists (DNSBLs).
Blacklists We Check
We check your domain and all associated mail server IPs against 12 major DNS-based blacklists, including Spamhaus ZEN (critical), Barracuda, SpamCop, SORBS, and more.
Being listed on a blacklist — especially Spamhaus — can cause your email to be rejected by most major mail providers. If you appear on a list, immediate investigation and delisting is required.
What this blacklist checker actually queries
A DNSBL is queried with an ordinary DNS lookup. To test an IPv4 address such as 203.0.113.25 against a zone, the octets are reversed and the zone name is appended: 25.113.0.203.zen.spamhaus.org. If the lookup returns an A record in the 127.0.0.0/8 range, the address is listed. If it returns NXDOMAIN, it is not. The return value is a code that tells you which sub-list matched.
The tool builds its list of addresses from your domain, not from a specific mail server. It resolves the A records of the domain itself, then resolves the MX hosts and checks the A records of the first three MX hosts. Every unique IPv4 address is tested against each IP-based zone. Two domain-based lists are queried with the domain name instead of an IP. Results are merged per zone, so a zone shows as listed if any one of your addresses is listed on it.
How a lookup is built
IP lookup: 25.113.0.203.zen.spamhaus.org -> A 127.0.0.2 (listed) / NXDOMAIN (clean) Domain lookup: example.com.dbl.spamhaus.org -> A 127.0.1.2 (listed) / NXDOMAIN (clean)
The 12 zones and how each is weighted
Each zone has a severity that drives both the verdict on this page and the blacklist component of the Email Security Score. Critical means one listing is enough for a fail result.
| Zone | Queries | Severity here |
|---|---|---|
| Spamhaus ZEN (zen.spamhaus.org) | IP; combines SBL, XBL and PBL | Critical |
| Spamhaus DBL (dbl.spamhaus.org) | Domain name | Critical |
| Barracuda (b.barracudacentral.org) | IP | High |
| SORBS SPAM (spam.sorbs.net) | IP | High |
| SpamCop (bl.spamcop.net) | IP | High |
| UCEPROTECT Level 1 (dnsbl-1.uceprotect.net) | IP | Medium |
| LashBack (blacklist.lashback.com) | IP | Medium |
| Invaluement (ivmsip.invaluement.com) | IP | Medium |
| Abuse.ch (spam.abuse.ch) | IP | Medium |
| DroneBL (dnsbl.dronebl.org) | IP | Medium |
| Mailspike BL (bl.mailspike.net) | IP | Low |
| Truncate (truncate.gbudb.net) | IP | Low |
The verdict is fail if any critical zone lists you, warn if only high, medium or low zones list you, and pass if nothing lists you. In the Email Security Score, the 20 blacklist points are all lost for a critical listing, reduced to 4 for a high-severity listing, reduced to 10 for medium or low only, and kept in full when clean.
Spamhaus replies of 127.255.255.254 and 127.255.255.255 are not listings. They mean the query source was not authorized or was rate limited, so the checker discards them rather than reporting a false positive.
How to read a result
- Look at the return code, not just the zone name. On Spamhaus ZEN, 127.0.0.2 and 127.0.0.3 are SBL (Spamhaus-identified spam sources), 127.0.0.4 to 127.0.0.7 are XBL (exploited or infected hosts), and 127.0.0.10 and 127.0.0.11 are PBL. PBL lists address ranges that should not send mail directly, such as dynamic consumer IPs. It is a policy list, not evidence that you sent spam.
- Check which IP was listed. If the listed address is your website host and not a mail server, the practical impact on email may be small. If it is your MX or outbound relay, it matters.
- A domain-based listing (DBL) follows the domain wherever it sends from. Changing IPs does not fix it.
- A clean result means those 12 zones did not list those addresses at the moment of the query. It does not mean your mail will be accepted everywhere.
Common findings: cause and fix
| Finding | Typical cause | What to do |
|---|---|---|
| Spamhaus ZEN, XBL code | A device or account on that IP is infected or was used for exploits | Find and clean the source, rotate credentials, then use the removal process on the Spamhaus lookup page |
| Spamhaus ZEN, PBL code | The IP is in a range that is not meant to send mail directly (typical on office broadband) | Send through your provider's authenticated relay or SMTP service instead of directly from the IP. Only the IP's owner or ISP can request a PBL exemption |
| Spamhaus ZEN, SBL code | Spamhaus has recorded spam activity or a spam-friendly host on the range | Read the SBL record, resolve the cause, and contact the network owner or Spamhaus as the record instructs |
| Spamhaus DBL | The domain appeared in spam, phishing or malware content | Check for compromised pages or forms, clean up, then request removal |
| SpamCop | Recipients reported your mail as spam | Reduce complaints with list hygiene and confirmed opt-in. SpamCop listings are designed to expire on their own once reports stop |
| Barracuda | Barracuda traffic or users flagged the IP | Use Barracuda's lookup page to see the status and submit the removal request |
| Only low or medium zones | Often a shared IP neighbor or a smaller list with limited reach | Note it, monitor, and prioritize anything on Spamhaus or high-severity lists first |
Step-by-step: getting delisted
- Confirm the listing from the zone operator's own lookup page, not only from this tool. The operator page shows the listing reason and the exact removal process.
- Stop the cause before asking for removal. Check outbound mail queues for unexpected volume, review recently created or compromised mailboxes, scan for malware, and make sure the server is not an open relay.
- Fix authentication so the next traffic is clean: a single valid SPF record, working DKIM signing and a DMARC record. Use the SPF, DKIM and DMARC checkers to confirm.
- Submit the removal request through the operator's official process and describe what you fixed. Do not pay anyone who promises guaranteed delisting.
- If the IP belongs to a hosting provider or ISP and not to you, ask them. Many listings cover the whole range and only the owner can resolve them.
- Re-run this checker after the operator confirms removal. DNS caching can briefly show the old status.
Some lists remove entries automatically after a period without bad behavior, and others require a manual request. Timelines vary by operator and by listing type, so use the figure on the operator's page rather than a generic estimate.
Limitations to keep in mind
- IPv4 only. The checker resolves A records, so IPv6 sending addresses are not tested.
- It checks the addresses published in your DNS (domain A record and up to three MX hosts). Your real outbound IP may be different, for example if you send through Google Workspace, Microsoft 365 or an email service provider. In that case, take the sending IP from a message's Received headers and check it directly on the operator's lookup page.
- A lookup that errors or times out is treated as not listed, so a clean row can occasionally mean no answer rather than a confirmed all-clear.
- Public DNSBL access has usage limits. Heavy querying through shared resolvers can be refused by some operators, which is why the Spamhaus error codes are filtered out.
- Zones change over time. Operators retire lists, change policies or alter who may query them. A zone that never lists anything is not proof that you are clean there.
- Listings are not equal. Mailbox providers such as Gmail and Microsoft use their own reputation systems in addition to, or instead of, public DNSBLs, so a clean result here does not guarantee inbox placement and a minor listing does not guarantee rejection.
Preventing relisting
- Send only to people who asked for your mail and remove hard bounces promptly.
- Enforce MFA on every mailbox and alert on unusual outbound volume.
- Publish SPF with -all or ~all, sign with DKIM and move DMARC toward enforcement so spoofed mail using your domain is rejected.
- On new IPs or domains, increase volume gradually. See the warm-up guide linked below.
- Re-check on a schedule, and after any change to your mail infrastructure.
Related tools and guides
Frequently Asked Questions
What is an email blacklist?
An email blacklist (DNSBL — DNS-based Blackhole List) is a real-time database of IP addresses or domains known to send spam or host malicious content. Major mail providers including Gmail and Microsoft 365 check these lists when receiving email. If your sending IP appears on a blacklist, your emails may be rejected or filtered to spam regardless of how well your SPF, DKIM, and DMARC are configured.
Which blacklists does this checker scan?
This tool checks your domain and all associated mail server IPs against 12 major DNSBL zones including Spamhaus ZEN (which combines SBL, XBL, and PBL), SpamCop SCBL, Barracuda BRBL, SORBS, and others. Spamhaus ZEN is the most widely used blacklist by enterprise mail servers and is the highest-priority listing to resolve if found.
How do I get removed from an email blacklist?
Each blacklist has its own delisting process. For Spamhaus: visit spamhaus.org/removal to check the listing reason and submit a removal request. For Barracuda: use barracudacentral.org/lookups. Before requesting removal, fix the underlying cause — compromised account, open relay, or malware — or you will be relisted. Most reputable blacklists delist within 24–72 hours of a successful request once the spam source is confirmed resolved.
How long does blacklist removal take?
Most reputable blacklists delist within 24–72 hours after a successful removal request, provided the spam source is confirmed resolved. Some blacklists automatically expire after 1–7 days of clean sending behavior. If you are relisted shortly after removal, it means the underlying issue — compromised account, misconfigured server, or shared sending IP used by spammers — has not been fully addressed.
Can my domain be blacklisted even if I do not send spam?
Yes. Your domain or shared sending IP can be blacklisted if: a user account was compromised and used to send spam; you share a sending IP with another domain that sends spam (common on shared hosting); a mail server was misconfigured as an open relay; or your domain appeared in spam content without being the actual sending domain. This checker identifies which specific blacklists have flagged you so you can investigate and request removal.