The MailAbuse Prevention Systems' Real-time Blackhole List is highlighted in a discussion of three techniques for making the users' mailboxes free of spam. Some of the techniques used by antispam tools are discussed, along with the advantages and disadvantages. A fast method for stopping spam at the desktop (if the mail provider does not filter spam) is also described. Smart users use caution when assessing advertisements, offers of money-making opportunities, ads for porno sites, offensive content, and suspect code in the message body or attachments. However, a good spam tool would allow several described variations, including software patches from a trusted source, to pass. Because a very large percentage of spam comes from a list of known servers, the connections of messages emanating from those servers can be blocked and the messages can be flagged as highly suspect, which eliminates a large amount of spam. Real-time Blackhole List (RBL), for instance, is a database that holds the addresses of systems that should be stopped from connecting from a Simple Mail Transfer Protocol (SMTP) server. Such products as Exchange 2003 and other advanced mail servers offer connection filtering, and some antispam tools also use an intelligent algorithm to find out if a message is spam. The Bayesian approach is one of the most precise and dependable ways to separate spam from legitimate messages.