Warming up
Transactional email API
Enter a domain or an IPv4 address to see if it is on an email blacklist. A domain is checked on 6 domain lists, and its own mail server's IP on 10 IP lists, with the reason and a removal link for any listing.
An email blacklist (also called a blocklist or DNSBL) is a DNS zone. Checking it is one DNS question: put the domain, or the IP with its four parts reversed, in front of the list's zone name and see what comes back.
The third answer is where free checkers go wrong. Spamhaus, SURBL and URIBL refuse queries from public resolvers like 8.8.8.8, and the refusal looks like a listing to a checker that treats every 127.x answer as a hit. This one asks through its own resolver and reads every list's codes individually, so a refusal shows as "No answer", not as listed and not as clean.
A domain listing (Spamhaus DBL, SURBL, URIBL) follows your domain wherever you send from, because filters look up every domain in the From address and in the links of a message. Switching email provider does not fix it. The usual causes are a new domain sending at volume from day one, spam trap hits from an old list, or a compromised site linked from your email.
An IP listing (Spamhaus ZEN, SpamCop, Barracuda) is about the server. If you send through Google Workspace or Microsoft 365 it is their IP and their problem, which is why this checker skips provider-hosted mail servers. If you run your own server or rent a dedicated IP, it is yours to fix. A Spamhaus PBL listing is a policy about residential IP ranges rather than a spam report, and the result says so.
A clean result here does not mean every provider trusts you: Gmail and Microsoft keep their own internal reputation, which no blacklist shows. The deliverability checker covers the authentication side (SPF, DKIM, DMARC), and what an email blacklist is, and how to get removed walks through delisting for each major list.
Stop the sending that caused it: pause the campaign, remove unverified or old contacts, and slow any new domain down to a warmup ramp. Then submit one removal request per list, from the link on the listing.
Warmerly's blocklist monitoring runs this same check on every sending domain daily, so the next listing reaches you as an alert instead of as a falling reply rate.
Enter your domain above. It is checked against 6 domain blocklists, including Spamhaus DBL, SURBL and URIBL, and if the domain runs its own mail server, that server's IP is checked against 10 IP blocklists including Spamhaus ZEN and SpamCop. Each list gets one DNS question, and a listing comes back with what it means and where to request removal.
Mail sent through Google Workspace or Microsoft 365 leaves from those providers' shared servers, which are not yours to check or delist. For those domains only the domain lists matter. If you send through your own server or a dedicated IP, enter that IP address directly.
The list did not give a verdict: it timed out, or it answered with a refusal code. Big lists like Spamhaus refuse queries that arrive through public DNS resolvers and signal that with an address in the same 127.x range they use for real listings. This checker queries through its own resolver and treats a refusal as unknown, never as a listing and never as clean.
Find and stop the cause first: a compromised account, a purchased or old list full of spam traps, or a sudden volume spike from a new domain. Then use the list's own removal form (linked from each listing above). Spamhaus and most other lists usually process a removal within a day once the cause is gone; asking before fixing it gets you relisted, often for longer.
For domains, Spamhaus DBL matters most, followed by SURBL and URIBL, which spam filters use to score the links and domains inside a message. For IPs, Spamhaus ZEN (which includes the SBL and XBL), SpamCop and Barracuda. We leave out SORBS (shut down in 2024) and UCEPROTECT (it charges for removal).
Check any domain's SPF, DKIM, DMARC, and MX records in seconds.
Validate an SPF record: one record, 10-lookup limit, and a safe ending.
Look up a DMARC policy, reporting address, pct and alignment.
Scan a subject line and email body for spam-trigger phrases.
Get a day-by-day sending ramp schedule for a new or existing mailbox.
Check text-to-HTML ratio, images, links, and tracking pixels in an email.
Warmerly checks your sending domains against these lists every day, alongside SPF, DKIM and DMARC, and warms your mailboxes so they stay off them. Free plan, no card. Paid plans from $19/month.
