HOW DOES EMAIL WORK?
The Internet mail system works because of SMTP, Simple Mail Transfer Protocol, SMTP is part of the TCP/IP suite of protocols.
SMTP is a protocol or set of rules that enables electronic mail to move smoothly through the Internet. Because of SMTP, a UNIX machine can send mail to a PC or Macintosh computer or vice versa.
Like other protocols of the Internet, SMTP is platform independent.