The intended audience is mail system administrators, who are already familiar with such acronyms as SMTP, MTA/MDA/MUA, DNS/rDNS, and MX records. If you are an end user who is looking for a spam filtering solution for your mail reader (such as Evolution, Thunderbird, Mail.app or Outlook Express), this document is not for you; but you may wish to point the mail system administrator for your domain (company, school, ISP...) to its existence.