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In the last 20 years, email has become one of the pillars of Internet. Today, almost everyone has at least one or more email addresses, but nobody realizes that the mail system was born as soon as the early 1960s. The community grew in the '70s, matured to big companies and institutes in the '80s, and the commercialized mail system in the '90s. In the last decade, spam and viruses have been endangering our trust in the whole mail system.
Though initially designed for plain text messages, today's mail programs enable users to send messages in HTML or RTF with multimedia documents attached. Modern systems have made sending emails an easy job, but at the same time few people understand what their PC is doing at this moment. This is a pity, because the basic email protocols use very simple processes.