This message may occur when a e-mail is sent to a 3Essentials Hosting Mail Server, by either another Mail Server or Mail Client and that sending IP (or server) is found on one of of the blacklists to which 3Essentials subscribes.

SpamCop is a spam blacklist (one of the several we use) that checks the IP Address of the sending mail server, if that mail server is found in the spam cop database then our server will simply drop the incoming connection.

In general if you get listed on SpamCop then it means someone using that mail server is sending a considerable amount of spam.

The owner of the sending server will need to contact SpamCop (http://spamcop.net) to get removed. The IP Address of the mail server will be listed in the email header of the bounce back message that is sent to the sender.