Internet Messaging

technologies for sending messages across the Internet. Leading technologies are shown below:Mail & NewsIMAP4 (Internet Message Access Protocol, Version 4)A still-evolving protocol that allows a client to access and manipulate e-mail messages on a server. IMAP4--designed for disconnected e-mail use--lets you perform such tasks as managing folders remotely, viewing just message subject lines, and selectively downloading messages and attachments based on various criteria (size or author, for example). IMAP4 also allows for shared mail folders.MIME (Multipurpose Internet Mail Extensions)A standard for transmitting nontext e-mail message attachments via SMTP. Most proprietary mail systems must translate any received MIME attachments through an SMTP gateway. See also MIME.NNTP (Network News Transfer Protocol)The protocol used by clients to post and retrieve messages to and from news servers, which host discussions. NNTP is also used by news servers to replicate newsgroup discussions.POP3 (Post Office Protocol, Version 3)An established protocol that lets Internet users send and retrieve e-mail to and from mail servers. POP3 provides simple store-and-forward e-mail functionality, compared with the richer IMAP4 specification.SMTP (Simple Mail Transfer Protocol)A standard protocol that defines how e-mail messages are transferred between servers. SMTP defines only ASCII text content, necessitating the MIME standard for nontext attachments.Uuencode/uudecodeAlong with MIME, another common method of sending binary e-mail attachments as plain ASCII text. See ASCII.. InfrastructureHTML (HyperText Markup Language)The simple document-formatting language of the World Wide Web. Netscape and other vendors have begun using HTML as their standard for rich-text formatting across all Internet applications, such as e-mail and newsgroup messages. See HTML.HTTP (HyperText Transfer Protocol)The protocol that negotiates delivery of text and other elements from a Web server to a Web browser. See HTTP.IIOP (Internet Inter-ORB Protocol)An evolving wire-level protocol that defines how distributed objects communicate with each other. IIOP--which is similar to Microsoft's Distributed Common Object Model (DCOM) specification--is based around the Common Object Request Broker Architecture (CORBA). In theory, any IIOP-compliant client software on any platform will be able to access the same object, a programming function that performs a specific task (such as authenticating a user against a server).LDAP (Lightweight Directory Access Protocol)An emerging directory service protocol that uses a subset of the X.500 directory standard to provide a common way to identify user and group information. It can be extended to provide information on other network resources.SecurityS/MIME (Secure MIME)A public-key encryption protocol for securely sending MIME attachments.SSL (Secure Sockets Layer)A protocol for sending encrypted information between a client and a server, often a Web server. SSL can work with any application-layer TCP/IP protocol and is most commonly used with HTTP.X.509 certificatesDigital-signature certihttp://www.trinity.edu/~rjensen/245refs.htm#cates that use public-key encryption for authenticating users. X.509 certificates can be issued by either a certificate authority (such as VeriSign) or an internal certificate server.(See also ASCII, E-mail, Internet, Internet Messaging, Mosaic, SLIP, and USENet)