2026-09-21 · IPV4 Scanner
Mail you send is bouncing, or arriving in spam folders, and someone has told you your IP address is blacklisted. It is worth knowing what that actually means before you start filling in removal forms, because a good proportion of the time the listing is a symptom rather than the problem.
A DNS blacklist — a DNSBL — is a published list of addresses believed to send spam, host malware or run open relays. Mail servers query them at the moment a connection arrives and decide whether to accept, flag or refuse it.
The mechanism is neat: the lists are published over DNS, so checking one is a fast lookup rather than an API call. A receiving server reverses your address, appends the list's domain and looks it up. An answer means listed.
There is no single authority. Dozens of lists exist, run by different organisations with different criteria and very different reputations. Some are careful and widely respected. Others list aggressively, delist slowly, and are used by almost nobody — which matters, because being on one of those is far less serious than being on a major one.
A compromised machine. The most common reason by far for a small business. One infected computer sending spam through your connection gets the whole address listed, and the machine usually shows no obvious symptoms.
A compromised mail account. A stolen password used to send bulk mail through your own server, which is entirely legitimate as far as the server is concerned.
An open relay or open proxy. A misconfigured server that accepts mail from anyone and forwards it. Automated scanning finds these quickly.
Poor list hygiene. Sending marketing to purchased lists, old addresses, or people who never opted in. Spam traps — addresses that exist only to catch this — are how the major lists detect it.
Your neighbours. On shared hosting or a dynamic residential range, you can be listed for what someone else did with an address near yours, or with the same address before you had it.
Simply being residential. Most lists include all dynamic consumer ranges as a matter of policy, because mail should not originate there. This is not a black mark against you, and there is no point requesting removal — the fix is to send through a proper mail service.
Our IP blacklist checker queries the major DNSBLs for an address and tells you which, if any, list it.
Check the address that actually sends your mail, which is often not the one you browse from. If you use a mail provider, their servers send on your behalf and their reputation is what matters — in which case a listing on your own address is irrelevant to your mail and may be causing you no problem at all.
Weigh the result by which list. A listing on one of the major, widely-consumed lists genuinely affects delivery. A listing on an obscure one that almost nobody queries may be affecting nothing.
Fix the cause first. This is not optional and not a formality. Requesting removal while still sending spam gets you relisted, often with a longer penalty, and some lists treat repeat requests without remediation as grounds for a manual listing that is much harder to shift.
So: find the compromised machine, change the stolen password, close the open relay, clean the mailing list. Check your own outbound mail queue — a queue full of messages to addresses you do not recognise is the answer.
Then request delisting. Each list runs its own form, and each publishes its own policy. Many delist automatically after a period with no further activity, which means the best action is frequently to fix the problem and wait.
Then verify the surroundings. Confirm reverse DNS for your sending address matches its hostname, that SPF, DKIM and DMARC are correct, and that your server is not an open relay. Our SPF, DKIM and DMARC checker covers the authentication side. These do not remove a listing, but their absence makes every future delivery problem worse.
Send through a reputable provider rather than from your own connection. Use a dedicated address for bulk mail so that a problem there does not poison your transactional mail. Authenticate everything. Monitor rather than waiting to be told — several services will alert you on a new listing, and hearing it from a customer is the expensive way to find out.
How long does it take to get delisted?
From hours to several weeks depending on the list and the reason. Many delist automatically once activity stops. Manual listings following repeated abuse take longest.
Can I be blacklisted without doing anything wrong?
Yes. Shared hosting, a recycled address, or being inside a residential range listed by policy will all do it. In the last case there is nothing to fix — send through a mail service instead.
Does a blacklisting affect my website?
Almost never. DNSBLs are consulted by mail servers. A few security products consult reputation data more broadly, but ordinary web traffic is unaffected.
Should I pay for expedited removal?
Be cautious. Reputable lists do not charge for removal. Some marginal lists exist mainly to sell it, which is a reason to question how widely they are used rather than to pay.
I fixed the problem but I am still listed. Why?
Delisting is not instant, and receiving servers cache results. Allow time for propagation, and confirm the cause is genuinely resolved rather than merely quiet.