Every spam filtering software, appliance, or outsourced service uses DNS Blacklist (DNSBL) servers as a first line of defense, but how effective are they?
BL-Monitor is a free visual tool to analyze DNSBL response times and effectiveness. It has a timing engine that simultaneously queries and measures multiple DNS blacklist server response times. It also tracks how many IP address are listed, unlisted or the server is unresponsive.
New to v2 is the ability to monitor your own local mail server to see if it has been accidentally blacklisted by any DNSBL server.