Reputation & monitoring
Email Blocklist Checker
Enter a domain or IPv4 address. We query every active free blocklist in parallel, surface which ones you are on, and point you at the right delist URL when you need it.
New to blocklists? Read What is an email blocklist in the Email Almanac.
How this tool works
How blocklist lookups actually happen
A blocklist is a DNS zone. Listed hosts and IPs get an A record on that zone; everything else returns NXDOMAIN. We ask the same question a mail server would ask, in parallel, across every active free list.
For an IPv4 lookup the octets get reversed, the blocklist zone is appended, and a normal DNS A query goes out. The presence of an answer is the listing; the answer code tells you which sub-list matched and why. Domain blocklists work the same way without the reversal, querying the domain followed by the zone directly.
Most blocklists run with no rate limits for low-volume queries and require a paid key past that volume. We use the public zones unless a Spamhaus DQS key is configured, in which case Spamhaus queries route through DQS automatically. The pool covers Spamhaus ZEN (SBL, XBL, PBL), Spamhaus DBL, Barracuda, SpamCop, the SORBS family, UCEPROTECT levels 1 to 3, and the other community-maintained lists with public DNS access. The result table tags every listing with a priority so you can triage by impact: a CRITICAL listing hits Gmail and Microsoft mail almost immediately; a LOW listing usually only affects a niche corner of the receiver world.
Lookups run server-side from this app. The input you enter is sent to public blocklist DNS zones as part of every normal DNS query a mail server would make. We do not log it and we do not share it elsewhere.
When to use it
Reach for it in these moments
The checker is a diagnostic. It is the first thing to run when something that used to deliver suddenly does not, and the last thing to confirm after a delisting request.
- A campaign started bouncing and you do not know why. Run your sending IP and your domain through the checker. A fresh Spamhaus SBL or Barracuda listing usually explains it in one click.
- You just submitted a delist request and want to confirm it went through. Re-run the check. If the entry is gone from every operator, you are clear; if it came back inside a day, the underlying cause is still active.
- You are auditing a domain or IP you just took over. An inherited listing on the previous owner’s mail flow is invisible until you check, and it is the cheapest source of mystery deliverability problems on day one.
- A vendor swears their IP is clean. Trust but verify. If the IP they sold you is on UCEPROTECT level 3, the deal is not what they said it was.
Email Almanac
Related questions to read next
The checker tells you which lists you are on. The Almanac explains how each operator decides what to list, what they want before they remove you, and how to keep from coming back.
Want continuous monitoring?
This tool is one-shot. The full Review My Emails platform watches every IP and domain you care about and notifies you the moment a listing appears.
Try it deeper with RME