INTERNET MAIL STANDARD

Internet e-mail functions through the use of a coordinated set of internet standards. Although many more standards actually apply to e-mail, virtually all mail servers and e-mail clients support at least the following basic set.

• SMTP (or RFC 2821) specifies the protocol by which e-mail is transmitted
• RFC 2822 specifies the basic format for e-mail
• MIME supplements the e-mail formatting rules to allow non-English text in both e-mail headers and bodies, and defines a mechanism for including non-textual attachments in e-mail bodies
• POP3 and IMAP4 specify e-mail retrieval protocols used by e-mail clients

This article is taken from Wikipedia. http://en.wikipedia.org/wiki/Internet_mail_standard