“While spammers will often alter their messages to look different, some are remarkably consistent. The table shows the top message FROM/SUBJECT line pairs over the last five years. We have also included our estimate of how many of each message was sent Internet-wide. To give you some sense, assuming an average message storage requirement of 4KB, over the last 5 years the total storage requirement imposed on the Internet by just the spammers sending the top-20 spam campaigns was over 2.5 petabytes.” WOW - Research from Project Honey Pot on spam.
