This test will check a mail server IP address against 116 DNS based email
blacklists. (Commonly called Realtime blacklist, DNSBL or RBL).
If your mail server has been blacklisted, some email you send may not be
delivered. Email blacklists are a common way of reducing spam. If
you don't know your mail server's address, start with a MX Lookup.
Or, just send an email to firstname.lastname@example.org
Stop dealing with blacklist problems.
Have more than 255 addresses?