Email Blacklists and Cloudmark's Sender Intelligence (CSI)

Return Path Infographic

Return Path recently published an infographic guide to public email blacklists.  As the infographic explains "Public email blacklists are lists of IP Addresses and domains that have been reported and listed as “known” sources of spam." These lists are used by both large email box providers and enterprises to make decisions about accepting or rejecting IP connections from Simple Mail Transport Protocol (SMTP) sources that are listed on a blacklist. Return Path's infographic notes that the Christmas season saw the most black-listings for the year. At Cloudmark we often notice that marketers and other email senders tend to become more aggressive with their sending practices around Christmas and other holidays.  They often send more frequently than usual, or to lists of addresses they haven't sent to before, or that they haven't sent to in a long time. Sending messages more frequently than email recipients want to receive them or more frequently than recipients are used to receiving them, often leads to more recipients voting that the marketing messages are spam, using the "This is spam" button in their email client. More frequent mailings can also magnify the impact of any spamtraps on a sender's email list. Sending mailings to old email lists that haven't been utilized since last year or longer also risks more recipients hitting the "This is spam" button. Additionally, old lists, that aren't actively being sent to, are more likely to contain emails that are no longer active, and have now been turned into spamtraps.  (Note: Inactive email accounts that are recycled in this way, usually have a long period of hard bouncing the messages before becoming a spamtrap, during which time senders should have removed the email address from their mailing lists.) [tweet_box]Sending to old, unused email lists risks more recipients hitting the "This is spam" button.[/tweet_box] Cloudmark provides a family of products called Cloudmark Sender Intelligence (CSI), which has functionality that overlaps with email IP Blacklists, but also includes a wider range of reputation information about the senders and IPs from which messages are originating.  Many of our customers use CSI information in combination with our powerful MTA policy engine (Cloudmark Security Platform) and Cloudmark Authority, our content filtering engine. Cloudmark's processes which determine which IPs get a poor or suspect reputation in our CSI products, take into account many different factors, including both spam trap hits and volume of trusted end user complaints (hitting the "This is spam" button), reputation of the reverse DNS of the IP, reputation of the IP block that the IP is part of, and traffic volumes over time which help measure likely use of the IP in a snowshoe attack. ISPs primarily want their email infrastructure to stay available and performing well, and for email recipients to receive the email that they want to receive.  But if as a sender or marketer your email is going to spamtraps or people are hitting the "This is spam" button, then it's not going to people who want it.