Blacklist Check

A DNSBL is a published list of IP addresses known for sending spam. Mail servers query these lists to decide whether to accept mail from a given IP.

Common causes are a compromised account sending spam, a misconfigured server acting as an open relay, or inheriting a "dirty" IP from a previous user. Each list has its own delisting process.

Fix the underlying issue (secure accounts, close open relays), then use the specific blacklist's removal request page. Listing this tool provides the source list for each hit.

It varies by list. Some remove an IP automatically after a period of clean behavior, while others require a manual delisting request and process it within hours to a few days once the underlying problem is fixed.

An IP blacklist flags the sending server address, while a domain blacklist (such as a URIBL) flags domains that appear in message bodies. A clean IP can still be listed if it links to a bad domain.

Not necessarily. Each receiver chooses which lists to consult and how to weigh them, so a listing on a minor blacklist may have little effect while a listing on a widely used one can cause broad rejections.

Send only to people who opted in, authenticate with SPF, DKIM and DMARC, keep bounce and complaint rates low, secure accounts against compromise, and never run an open relay.