- Delisting is a sequence, not a form: diagnose the listing, fix the root cause, then request removal.
- Blocklists track either your sending IP or your domain, so scan both.
- Spamhaus and Barracuda offer free self-service removal; SpamCop and UCEPROTECT Level 1 expire on their own.
- SORBS shut down in 2024, Gmail has no public blocklist, and Outlook blocks are handled through Microsoft's sender support.
- You should never have to pay anyone to be delisted from a reputable list.
- Getting off the list stops hard blocks, but provider reputation can take several more days to recover.
A blocklist listing can stall your email overnight. Messages that reached the inbox yesterday start bouncing with policy errors or quietly disappearing into spam. The good news is that delisting is a well understood process, and most listings can be cleared in a day or two once you fix what caused them.
This guide explains how email blacklists work, how to confirm where you are listed, why listings happen and exactly how to get removed from each major list without being re-listed a week later.
What an email blacklist is
An email blacklist (the industry increasingly says “blocklist”) is a public database of IP addresses or domains flagged as sources of spam or abuse. Most are DNS-based blocklists, or DNSBLs: receiving servers query them in real time by DNS as your message arrives.
The mechanics are simple. When your server connects from IP 192.0.2.10, the receiver reverses the octets and looks up 10.2.0.192.zen.spamhaus.org. An answer in the 127.0.0.x range means listed. No answer (NXDOMAIN) means clean. Domain lists work the same way using the domain name.
There are hundreds of lists, but they are not equal. A listing on Spamhaus affects a huge share of the internet’s mail. A listing on an obscure list nobody queries may affect almost nothing. Lists also track different things:
- IP lists flag the server your mail comes from. On shared ESP IPs, that server is shared with other senders.
- Domain lists flag domains that appear in spam, either as the sender or in links. These follow you wherever you send.
What a listing actually does to your mail
A listing does not block your mail by itself. What matters is how each receiver uses the list. Some reject mail outright at connection time, so you see a bounce such as 554 or 550 naming the list. Others use a listing as one input to a spam score, so your mail is accepted but lands in spam more often. Many large consumer providers rely mostly on their own data and consult public lists lightly or not at all.
That is why the same listing can cause a flood of rejections at business recipients and barely register at Gmail. It is also why you should prioritize removal from the lists that your actual recipients use. If most of your audience is B2B, Spamhaus and Barracuda listings matter a great deal.
How to find out if you are listed
Run a scan
Enter your domain and your sending IPs in the Blacklist Checker. It queries the most widely used lists at once and shows every hit. If you do not know your sending IP, look at the Received headers of a message you sent, or paste the full headers into the Header Analyzer.
Record what each listing tracks
For each hit, note the list name and whether it lists your IP or your domain. That tells you where to look for the cause and which removal page to use.
Read your bounce messages
Rejections often name the list outright. A 554 or 5.7.1 error that says “listed by Spamhaus” or includes a Barracuda reference is a direct pointer. Microsoft blocks usually mention its own reference codes rather than a public list.
Check the surrounding health
Run the Sender Reputation Checker as well. Listings often come with other problems, such as broken authentication or a missing PTR record, that make the underlying situation worse.
Why domains and IPs get listed
Listings are almost never random. They reflect behavior the operator treats as a spam signal.
| Cause | What you might notice | Fix |
|---|---|---|
| Compromised account or server | Outbound mail you did not send, odd login locations, a queue full of unfamiliar messages | Reset passwords, enable two-factor, remove malware, patch the breached CMS or plugin |
| Open relay or misconfiguration | Your server forwards mail for unauthenticated senders | Require SMTP authentication, restrict relaying |
| Spam trap hits | Mail to addresses that never subscribed, often from old or bought lists | Stop buying or scraping, use confirmed opt-in, prune inactive addresses |
| Poor list hygiene | Hard bounces above 2% | Verify the list, suppress bounces automatically |
| Complaint spike | Complaint rate above 0.1% in feedback loops | Mail only engaged recipients, make unsubscribe one click |
| Volume spike | A sudden 5x to 10x jump | Warm up new volume over two to four weeks |
| Shared IP neighbor | You did nothing different, but the pool IP is listed | Ask your ESP to investigate or move you |
| Spammy links | A domain list hit on a link or tracking domain | Remove the link, check URL shorteners and third-party domains |
Spam traps deserve a special mention. Pristine traps are addresses that were never used by a real person and exist only to catch harvested or purchased data. Recycled traps are old, abandoned addresses that a provider turned into traps after a long period of bouncing. Hitting either says your list was not built or maintained properly. The list hygiene guide and the bounce rate guide cover prevention.
How to get delisted, step by step
1. Read the listing reason
Open the operator’s lookup page for the list you are on. Most show a reason or reference, and exploit-based lists often name the malware or botnet they detected.
2. Fix the underlying problem completely
Match the reason to a cause from the table above and resolve it. Clean the infected machine, close the relay, remove the bought segment, suppress the complainers, fix authentication. If you are not sure the fix worked, wait a day and watch outbound logs before moving on.
3. Submit one removal request
Use the operator’s official self-service form. Explain briefly and honestly what happened and what you changed. One request is enough. Repeated requests do not speed anything up and can annoy the humans who review them.
4. Allow time to propagate
Some lists update within minutes, others take a day or two. Receivers also cache DNS answers, so a few hours after removal some servers may still see the old result.
5. Re-scan, test and monitor
Run the Blacklist Checker again, send a small batch to your most engaged subscribers, and scan weekly for the next month in case the problem was not fully gone.
The major blocklists and how to get off each one
| Blocklist | What it lists | How removal works | Typical timing |
|---|---|---|---|
| Spamhaus SBL | IPs and ranges operated by or serving spammers | Ticket-based review through the Spamhaus checker after the issue is fixed | Days, depends on case |
| Spamhaus XBL (includes CBL) | Compromised or infected hosts, botnet traffic | Clean the host, then self-service removal via the Spamhaus checker | Minutes to hours |
| Spamhaus PBL | IP ranges that should not send direct-to-MX (such as residential) | Not a penalty; the IP owner can request exclusion if it is a real mail server | Minutes |
| Spamhaus DBL | Domains found in spam, including in links | Fix the cause, request removal via the Spamhaus checker | Usually within a day |
| Barracuda (BRBL) | IPs with poor reputation from Barracuda sensors | Free removal request at Barracuda Central | Around 12 to 24 hours |
| SpamCop | IPs reported by SpamCop users | No request; listings expire once reports stop | Usually within 24 hours |
| UCEPROTECT Level 1 | Individual IPs seen hitting its traps | Expires automatically; paid express removal is optional and unnecessary | About 7 days |
| UCEPROTECT Levels 2 and 3 | Whole ranges or networks with many listed IPs | Escalated to your provider; expires as their abuse clears | Varies |
| SORBS | Formerly spam and open-relay lists | Shut down in 2024; any listing still shown is stale | Not applicable |
| Microsoft (Outlook, Hotmail) | Private IP blocks, no public list | Submit the delisting form through Microsoft’s sender support, check SNDS | 24 to 48 hours after approval |
| Gmail | No public list; reputation-based filtering | Fix the cause, monitor Google Postmaster Tools | Days to weeks |
Spamhaus
Spamhaus is the most widely used operator, so a listing here has the broadest effect. Start at the Spamhaus checker page, which tells you which zone lists you and why. XBL listings (which now include the old CBL data) almost always mean a machine on your network is infected or a web form is being abused; clean it first, then use self-service removal. SBL listings are more serious, involve human review, and usually require you to show that the spam source has been dealt with. DBL listings apply to domains, often because they appeared in links in spam.
Barracuda
Barracuda’s reputation list is used by organizations running Barracuda security appliances, which include many businesses and schools. Check your IP on Barracuda Central, fix the cause, and submit the free removal form with a contact email and a short explanation.
SpamCop
SpamCop is driven by user reports. There is no removal form because the listing expires by itself, typically within a day, once the reports stop. The fix is to stop sending the mail that generated the reports: tighten permission, make unsubscribing easier and check for compromised accounts.
UCEPROTECT
UCEPROTECT uses levels. Level 1 lists individual IPs and expires on its own after about a week without new trap hits. Levels 2 and 3 list whole ranges and hosting networks, which can sweep in senders who did nothing wrong. These clear when the provider’s overall abuse drops. UCEPROTECT offers paid express removal; with Level 1 expiring anyway, most deliverability engineers advise against paying.
SORBS
SORBS was shut down in 2024 and is no longer maintained. If an old tool still reports a SORBS listing, you can ignore it. If a receiver is still rejecting you citing SORBS, contact that receiver, since their configuration is out of date.
Microsoft and Gmail
Neither publishes a public list. Microsoft blocks show up as rejections such as 550 5.7.1 with an internal reference (for example an S3150 code). Register your IPs in Microsoft SNDS, then submit the delisting request through Microsoft’s sender support form for Outlook.com. Gmail filters on its own reputation data, so the path is to fix authentication, complaints and list quality and track progress in Google Postmaster Tools. Temporary deferrals like 421 or 4.7.0 during recovery are normal.
Writing a removal request that works
Removal forms are read by people or checked by automated systems that look for evidence of a fix. Keep the request short, specific and honest. Something like this works well:
IP / domain: 198.51.100.20 (mail.example.com)
Listed on: Barracuda BRBL, detected 2026-09-15
What happened: A contact form on our website was abused by bots to send
messages through our mail server over two days.
What we fixed: Removed the vulnerable form plugin, added CAPTCHA and rate
limiting, rotated SMTP credentials, and confirmed no further
unauthorized mail in our outbound logs for 48 hours.
Contact: postmaster@example.comAvoid blaming the list, demanding immediate action or submitting several times. If the form asks for a reason and you honestly do not know it, say what you investigated and what you found, and fix the most likely causes before you submit.
Do not forget your link and tracking domains
Domain blocklists such as the Spamhaus DBL and URIBL check every domain in the body of your message, not just the sender. That means a listing on a domain you link to can get your mail filtered, even if your own domain and IP are clean.
Common culprits:
- Public URL shorteners, which are shared with spammers and often listed.
- Old tracking or redirect domains left over from a previous ESP.
- Affiliate or partner domains you link to in promotions.
- Image hosts or file-sharing links used in campaigns.
Scan your branded tracking domain with the Blacklist Checker along with your main domain, avoid shorteners entirely and use a custom tracking domain on your own brand where your ESP supports it.
If you are on a shared IP
When your ESP’s shared IP is listed, the listing is usually caused by another customer. You cannot delist an IP you do not control, and you should not try. Send the listing details to your ESP’s support team. Reputable providers monitor their pools, remove the offending sender and move customers to clean IPs quickly. If listings on your pool keep recurring, that is a signal to review your provider; our shared vs dedicated IP guide explains when moving to your own IP makes sense.
How long recovery takes
Delisting and recovery are two different things. Getting off the list stops the hard blocks at receivers that use it. But Gmail, Outlook and Yahoo keep their own reputation data, and that recovers more slowly. Expect:
- Exploit and XBL listings: minutes to hours after cleanup.
- Spamhaus DBL and Barracuda: roughly half a day to a day.
- SpamCop: about a day after reports stop.
- UCEPROTECT Level 1: about a week.
- Mailbox provider reputation: a few days to several weeks, depending on how bad it got.
During recovery, send only to your most engaged recipients and ramp back up gradually, as described in the sender reputation guide.
How to stay off blocklists
Prevention is far easier than removal.
- Keep your list clean. Confirmed opt-in, first-bounce suppression, sunset inactive subscribers, never buy or scrape lists.
- Authenticate everything. SPF, DKIM and DMARC at
quarantineorreject. Check with the SPF Checker and DMARC Checker. - Secure your infrastructure. Patch mail servers and web forms, close open relays, use two-factor on every mail account, and set a proper PTR record with the Reverse DNS Checker.
- Protect your forms. Add CAPTCHA or honeypot fields and confirmed opt-in so bots cannot fill your list with trap addresses.
- Send predictably. Steady volume, easy unsubscribe and gradual warmup for any big increase.
- Monitor. Scan your domain and IPs monthly with the Blacklist Checker so you catch a listing in days, not after a campaign has already failed.
Most of these habits are the same ones that drive good inbox placement overall. The deliverability playbook puts them in priority order.
Frequently asked questions
How do I know if I am on an email blacklist?
Run your domain and sending IP through the Blacklist Checker, which queries the major lists at once. Signs you may be listed include a sudden rise in rejections such as 5.7.1 or 554 that mention a list by name, or a drop in delivery at many unrelated receivers on the same day.
How long does it take to get off a blacklist?
It depends on the list. Spamhaus self-service removals often clear within a day. Barracuda typically takes 12 to 24 hours after review. SpamCop listings expire within about a day once reports stop, and UCEPROTECT Level 1 drops after roughly seven days. Mailbox provider reputation may lag a few more days.
Should I pay for a fast delisting service?
No. Reputable lists such as Spamhaus, Barracuda and SpamCop never charge for removal. UCEPROTECT offers paid express delisting, but Level 1 expires on its own, so paying is rarely worth it. Third-party services that promise removal for a fee cannot do anything you cannot do yourself for free.
Why was I re-listed right after being removed?
Because the cause was still active. Operators keep detecting the same compromised account, trap hits or complaints and list you again, sometimes with a longer penalty for repeat offenders. Confirm the fix is complete, wait until you see no new abuse, then request removal once.
Does Gmail use a blacklist?
Gmail does not publish a public blocklist you can query or be removed from. It filters based on its own reputation data, which you can view in Google Postmaster Tools. If Gmail is rejecting you, fix authentication, complaints and list quality, then let reputation recover over days to weeks.
I am on a shared IP and got listed. What should I do?
Contact your ESP right away with the listing details. On shared pools the provider owns the IP and is responsible for delisting and for removing the sender who caused it. Most reputable ESPs move affected customers to a clean pool quickly. If it keeps happening, consider a better-policed provider or a dedicated IP at high volume.
Can a domain be blacklisted, not just an IP?
Yes. Domain lists such as the Spamhaus DBL and URIBL flag domains that appear in spam, including in links. A domain listing follows you to any IP or ESP, so it can affect you even after switching providers. Check both your sending domain and any link or tracking domains.