• How to Avoid Being Blacklisted
  A blacklist usually refers to a list of email or IP addresses known to send spam emails or some other type of unsolicited messages. Such lists are currently used by mail servers for filtering incoming emails and blocking the ones listed, in order to improve mail security and integrity. The blacklist is also the opposite of what is called a whitelist.
  in Public bookmarks with blacklist email mail security spam unsolicited

blacklist from all users