DNS Blacklist Checker

Checks an IP address against more than ten DNS-based blacklists (DNSBLs) and mail-specific RBLs used by spam filters worldwide. Getting listed on even one of these can silently tank mail deliverability — messages get bounced or quietly routed to spam with no notification to the sender. Queries route through our own private resolver rather than a public one, since most RBL operators explicitly prohibit high-volume lookups through shared public DNS. Worth checking any time outbound mail volume increases, after a server IP changes hands, or as a first move when deliverability complaints start coming in.

Getting delisted after fixing the underlying issue isn't instant — most blacklist operators require manually requesting removal, and some enforce a mandatory waiting period regardless of how quickly the cause was resolved.

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