- Describes the widely implemented Simple Mail Transfer Protocol (SMTP) designed to transfer mail reliably and efficiently and relay mail across transport service environments.
- Describes the Internet Message Access Protocol (IMAP), which allows a client to access and manipulate electronic mail messages on a server, and permits manipulation of remote message folders.
- Defines a portion of the Management Information Base (MIB) for use with network management protocols, and extends the basic Network Services Monitoring MIB to allow monitoring of Message Transfer Agents (MTAs).
- Describes the widely implemented Simple Mail Transfer Protocol (SMTP) designed to transfer mail reliably and efficiently and relay mail across transport service environments. Obsoletes RFC 821, 974, 1869.
- Defines a framework for extending the SMTP service by defining a means whereby a server can inform a client as to the service extensions it supports.