Lookup
Blacklist checker
Check an IP or domain against Spamhaus (where configured) and a curated set of open DNS blocklists, on demand.
Results
Enter an IP or domain and check it to see results here.
Results are best-effort: DNSBL zones can lag real sending activity, and rows marked Unavailable need a configured lookup key MailSends does not have in every environment.
Additional context
Reverse DNS (for an IP) or MX/A record presence (for a domain) will show up here.