Electronic mail protocols

Two types of protocols are used for the transmission of electronic mail. They are SMTP and MIME. SMTP supports only text messages while MIME supports both text message transmission and multimedia information transmission. SNMP is simple network management protocol which is designed to operate in both the TCP/IP and OSI environments. Simple mail transfer protocol (SMTP) which is defined in RFC 821 is the standard protocol for the transfer of mail between hosts in the TCP/IP environment. Here user creates mail which is comprised of a header that includes recipient’s e-mail address and other information and a body containing the message to be sent. These messages act as input to SMTP sender program. This program is usually an always-present server program on the host. Multipurpose internet mail extensions (MIME) which is an extension to the RFC 822 framework support multimedia information transfer. In MIME, five new message header fields are defined. It also defines a number of content formats and transfer encodings. The five header fields defined in MIME are MIME version, content type, content-transfer encoding, content-ID and content-description. Different MIME content type formats are test type, multipart type, message type, image type, video type, audio type and application type. MIME transfer encodings provides reliable delivery across the largest range of environments. The different MIME transfer encodings are 7-bit, 8-bit, binary, quoted-printable, base 64 (radix-64) and x-token.