The SMTP message format was defined by the RFC 822 standard, and in 2001 the RFC 2822 standard superseded the RFC 822 standard. These standards are suitable to transfer data in the ASCII format. It soon became clear that this standard was not suitable for many users’ needs; users wanted to send emails containing texts written with other character sets, formatted text, images, sounds, binary files, and so on. Recently, a new need is to send secure email with attached encrypted or electronically signed messages.
The users’ needs quickly exceeded the limit of the RFC 822 standard and the Multipurpose Internet Mail Extension (MIME) , specified by RFC 2045-2049, was therefore introduced. Today, RFC 2048 has be superseded by RFC 4288 and RFC 4289.
The problem of sending emails containing other kinds of data than text in the ASCII code can be solved without MIME; the message just needs to be encoded into ASCII before sending. To read it, the recipient first has to decode...