Checks an IP — or a domain’s IP — against a curated set of reputable DNS blocklists. Enter your mail server’s sending IP for the most useful result.
Why your email might be getting blocked
If your messages are bouncing or vanishing into spam folders, a blacklisted sending IP is one of the first things to rule out. Receiving mail servers check the sender’s IP against DNS blocklists (DNSBLs) in real time — and a listing on a list they trust means your mail is rejected or junked before anyone reads it. This tool checks your IP against a curated set of reputable lists at once and tells you exactly where you stand.
How a DNSBL check works — the receiver queries the reversed IP against each list.
Not all lists carry the same weight
A listing is only as important as the receivers who use that list. Spamhaus and Barracuda are weighted heavily by Microsoft and Google, so a listing there genuinely blocks delivery. Other lists are broader or more aggressive — UCEPROTECT Level 1, for instance, can list a whole hosting range — and major providers give them less weight. We show every result with its source so you can judge correctly, rather than panicking over a low-impact listing. Lists we know to be defunct (such as SORBS, which shut down in 2024) are deliberately excluded so you’re never checked against a dead service.
Getting delisted — fix the cause first
Requesting removal before fixing the underlying problem just gets you relisted. Common causes are a compromised device or mailbox sending spam, an open relay, a leaked password, or a brand-new IP with no sending reputation. Clean that up, then use the per-list delisting links the tool shows to request removal. Some lists expire listings automatically once abuse stops; others need a manual request and a short wait.
Staying off blacklists for good
Reputation is earned and easily lost. Authenticate every message with SPF, DKIM and an enforced DMARC policy; secure every mailbox with strong passwords and MFA so it can’t be hijacked to send spam; and warm new sending IPs up gradually. Run the all-in-one Email Security Checker to confirm the authentication side is solid.
📨 Mail not landing in the inbox? Servnet fixes sending-IP reputation, authentication and delisting end-to-end. Get deliverability help →
Email blacklists — common questions
What is an email blacklist (DNSBL)?
A DNSBL — DNS-based blocklist, also called an RBL — is a published list of IP addresses known for sending spam or abuse. Receiving mail servers query these lists in real time and reject or junk mail from listed IPs. This tool checks an IP against a curated set of reputable DNSBLs at once.
How do I know if my mail server’s IP is blacklisted?
Enter your sending IP (or your domain — we’ll resolve its IP) and check. Each list shows clean, listed, or no-response. A listing on a major list like Spamhaus or Barracuda is the kind that actually blocks delivery to large mailbox providers, so prioritise those.
Which blocklists do you check?
A curated set of reputable, widely-used DNSBLs including Spamhaus ZEN, Barracuda and SpamCop, plus several others — all verified to answer reliably from our infrastructure. We deliberately exclude defunct lists (e.g. SORBS, which closed in 2024) so results stay accurate.
I’m listed — how do I get removed?
First fix the cause: a compromised device or account sending spam, an open relay, a mailbox with a leaked password, or simply a new IP with no sending history. Once the source is clean, use the delisting link shown for each list to request removal. Some lists auto-expire listings after the abuse stops; others need a manual request.
Should I worry about being on one list?
It depends which one. The big mailbox providers (Microsoft, Google) lean heavily on Spamhaus and Barracuda, so a listing there is serious. Some lists (for example UCEPROTECT Level 1, or aggressive policy lists) are broader and carry less weight with major receivers. The tool shows every result so you can judge by which list is involved.
Why might a list show “no response”?
Some DNSBLs rate-limit or occasionally fail to answer a query. We mark that as “no response” rather than guessing “clean”, so you’re never given a false all-clear. Re-check in a moment, or confirm directly on that list’s own lookup page.
How do I stay off blacklists in the first place?
Authenticate your mail with SPF, DKIM and an enforced DMARC policy; keep your sending IP’s reputation clean; secure every mailbox with strong passwords and MFA; and warm up new IPs gradually. Our Email Security Checker covers the authentication side; Servnet can manage the rest.