Internet e-mail functions through the use of Internet Standards. Although many more standards actually apply to e-mail, virtually all and support at least the following basic set.
SMTP (or ) specifies the protocol by which e-mail is transmitted
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