Problems sending emails? Here you can check whether the mail server IP address you send emails from, has been blacklisted for sending unsolicited bulk email (spam) by one or more of the many DNS-based blacklists providers. If the IP address is listed, chances are that many ISPs refuse accepting e-mails coming from that IP address.
Email blacklists are also known as DNS-based Blackhole List (DNSBL) or Real-time Blackhole List (RBL)
DNS Radar currently checks more than 80 blacklists in real time, providing non-cached, accurate resuts.