Pro move: type dmarc:yourdomain.com or blacklist:1.2.3.4 straight into the box — it switches tools for you.
About this tool. Being on a DNS blocklist quietly kills your email deliverability. This check queries close to 40 respected public blocklists for your IP (and domain blocklists for domains) — the same roster the big monitoring tools use. Spamhaus and a few others refuse anonymous queries from shared resolvers; when a Spamhaus Data Query Service key is configured we query their authoritative keyed zones directly, otherwise those are flagged honestly. Sign in to monitor a domain or IP daily from your dashboard.