Check if your domain or mail server is on a spam blacklist.

A blocklist check has to look at your domain and your mail server, not your website.

Receiving servers ask two questions about a message when it arrives. Is the domain in it on a list of domains seen in spam? And is the server that delivered it on a list of servers that send spam? This check asks both: your domain on 3 domain lists, and the IP of the server your domain's mail runs on on 13 IP lists.

The old version of this page looked up the IP of the domain's website and checked that. A website usually sits on a host that sends no mail at all, so a clean result there told you nothing about your email. We now take the IPs from the domain's MX records and from single addresses in its SPF record, up to three of them.

When the domain's mail runs on Google Workspace, Microsoft 365 or another provider whose servers are shared with many other domains, there is no IP of your own to look up, so the report checks the domain alone and says why. That is the setup most cold email domains use, and the right one: your reputation then rides on the domain and its records, which the other four rows of the report check.

These are the 16 blocklists we check, and a listing on 4 of them fails the check.

The lists the Emailchaser app checks for its customers' sending domains, less the ones that cannot give an answer from our servers: one has closed, one only answers lookups that carry an account key, and two refuse or ignore lookups from cloud servers. A list we cannot ask is left out rather than shown as clean.

A list that does not answer is never counted as clean.

A blocklist answers a lookup in one of two ways: an address in 127.0.0.x means listed, and no answer at all means clean. That second case is the trap. A list that has shut down, or that refuses to answer you, also gives no answer, and most checkers count it as clean. A report that says "clean on 80 lists" can mean far fewer lists actually looked.

So before we trust a list, we ask it about its own test entry, an address every working copy of the list must answer as listed. A list only counts as checked when that test answered, through the same connection, minutes before. A list that failed the test, timed out or refused us shows as not checked in the report, and the number of lists checked counts only the lists that answered.

Spam traps, complaints and bounces are what put a sender on a list.

The fastest route onto a list is a spam trap. Some traps are addresses that were never real inboxes, seeded where only a scraper would find them, so mailing one shows the list was scraped or bought. Others are real addresses a provider abandoned and later turned into traps, so mailing one shows the list was never cleaned. A handful of hits can be enough.

The other triggers are complaints and bounces. Lists such as SpamCop are fed by recipients pressing the spam button, so a climbing complaint rate can list you within hours. A high hard-bounce rate tells every receiver the list was never checked. Running your list through the bulk email verifier before you send strips out the dead addresses that recycled traps hide among.

Getting off a blocklist starts with fixing what put you there.

1. Find the list in the report. Each listing names the list and links to its removal page.
2. Fix the cause: stop the campaign that drew complaints, clean the list, or secure the account or server that sent the spam.
3. Then ask for removal on the list's own page. Asking before the cause is fixed gets you listed again.
4. Run the check again. Most lists update within hours of a removal.

Some lists clear on their own. SpamCop removes an IP automatically 24 hours after the last spam report (SpamCop). Barracuda takes removal requests and says it typically processes them within 12 hours (Barracuda). PSBL lets you remove an IP yourself. Both read on 6 October 2026.

A listing either stops your mail at the door or sends it to spam.

A server set to block on a listing refuses the message as it arrives, so it never lands anywhere. That is common on self-hosted servers and on filtering gateways. A server that treats the listing as one signal among many accepts the message and scores it down, often into spam. Either way your copy never gets a fair read.

Who you email decides how much a listing costs you. Of the 499 business domains we measured on 5 Sep 2026, 42.9% sit behind a security gateway and 9.6% run a mail server of their own or one we do not recognise; 26.1% use Microsoft 365 and 18.8% Google Workspace. Every one of these setups can consult a blocklist before it accepts mail.

A clean result is necessary for good delivery, but not enough on its own.

Being off every list means nobody is blocking you outright. Whether your mail reaches the inbox still depends on your SPF, DKIM and DMARC records and on your sending history. Check the records on the SPF, DKIM and DMARC checkers, and give a new mailbox a history before it sends a campaign by warming it up.

People also land here from the other direction, checking a domain that emailed them. If that is you, the blocklist result is one signal and the sender is the other, so check who is behind the address as well.

Common questions about email blacklists

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