About the Blacklist Checker
Mail servers reject or junk mail from IP addresses on DNS-based blocklists (DNSBLs). This tool checks an IPv4 address against five lists that allow free public queries: SpamCop, PSBL, Mailspike, UCEPROTECT Level 1 and DroneBL. Enter a domain and it checks the domain's A records and the A records of its MX hosts, up to 8 addresses.
Each lookup reverses the address and queries it under the list's zone; 7.113.0.203.bl.spamcop.net checks 203.0.113.7. An answer of 127.0.0.x means listed, and the list's TXT record, when it has one, gives the reason. Some lists answer 127.255.255.x when they refuse a query, for example because of rate limits; those show as Couldn't check, not as listed.
Spamhaus and Barracuda aren't checked. Spamhaus doesn't allow queries through shared resolvers or for commercial services without a paid account, and Barracuda requires registration. Use their own lookup pages. Most DNSBLs only cover IPv4, so IPv6 addresses aren't checked.
How to use it
- Enter an IPv4 address, or a domain to check its web and mail servers.
- Select Check lists.
- For a listing, follow the Delist link to the list's removal or lookup page.
Examples
- Check 1.1.1.1: Cloudflare's resolver, which sends no mail.
- Check example.com: a domain with a null MX, so only its A records.
Common questions
How do I get delisted?
Fix the cause first: a compromised account, an open relay or a script sending spam. SpamCop and UCEPROTECT listings expire on their own once the spam stops; PSBL and Mailspike have removal forms.
Does one listing matter?
Large providers rely mostly on their own data, so one small list rarely blocks mail by itself, but it shows something sent spam.
Why is my shared hosting IP listed?
Another customer on the same server may have sent spam. Ask your host.
Related tools
- SPF, DKIM & DMARC Checker: check the domain's mail authentication.
- IP Lookup: find the owner and abuse contact of an address.