IP Blacklist Checker
Check an IP against common DNSBL zones.
Use the IP Blacklist Checker tool
What this ip blacklist checker does
IP Blacklist Checker converts an IPv4 address or domain into the reversed form that DNSBL zones use, then queries each zone over DNS-over-HTTPS. A listed answer includes the returned code, which can hint at the reason for listing. A clean answer means the zone did not return a listing at that moment.
DNS blocklists differ in purpose, coverage and how quickly they expire entries. Some refuse queries from public resolvers, so the tool shows “unavailable” rather than pretending the address is clean. Being on a list also does not by itself mean mail will be rejected; the receiving provider decides.
Why use it
- Check whether a mail server's IP appears on major blocklists.
- Confirm a listing is gone after a delisting request.
- Understand why a domain's mail lands in spam folders.
How to use it
- 1Enter an IPv4 address or a domain that resolves to one.
- 2Run the check and wait for each zone to answer.
- 3Read listed, clean and unavailable rows separately.
- 4For a listing, open the zone's own page and follow its removal process.
Worked examples
Clean address
Input
A residential IP with no active listings
Output
Most zones answer with an NXDOMAIN-style response, shown as clean.
Listed address
Input
An IP present in a zone
Output
The row shows the returned 127.0.0.x code for that zone.
Common mistakes
- Treating one clean result as proof the address cannot be blocked.
- Ignoring unavailable rows and assuming they were clean.
- Checking a shared hosting IP and blaming your own mail configuration.
Frequently asked questions
Which blocklists are queried?
A fixed set of common public DNSBL zones. The exact list is shown with the results.
Why are some zones unavailable?
The zone may refuse queries from public resolvers, be offline, or rate-limit the resolver used.
Can I check an IPv6 address?
Most DNSBL zones only cover IPv4. Use the IPv4 address of the sending server where possible.
Does a listing stop my email?
Not automatically. Providers weigh many signals. A listing increases the chance of rejection or spam filtering.