Electronic mail has all but replaced most forms of written communication. When was the last time you received snail-mail from someone? Banks don’t count! Contrary to popular belief, e-mail was present before the Internet was created. In fact, the tools used for e-mail today were the building blocks of the Internet. E-mail moved from being just another application of a network to becoming the killer app of the ARPANET and later, the Internet. So how does email work? Well, it’s not rocket science, but a detailed explanation would require more than a chapter. In a nutshell, messages (mails) are exchanged between hosts using the Simple Mail Transfer Protocol (SMTP) with software such as Sendmail. Users download their messages (received mails) from servers, usually using either the POP or IMAP protocols.
With the increasing number of Internet users, e-mail services, too, have undergone drastic changes. One of the most apparent changes has been the explosion in storage space. With Google entering the mail arena with its free Web mail service, GMail, most providers are now in the race to provide more and more mail storage space. Though the Internet has innumerable number of mail service providers, Yahoo!, GMail and Hotmail remain the most widely used.