Pine stands for "Program for Internet News & Email" (or "Pine Is No-longer Elm"). It is a text based E-mail client developed by the University of Washington.
Pine's original purpose back when it was developed in 1989 was to be a basic E-mail program that administrative staff at UW could use. They had been using a derivative of UCLA's "Ben", but it became too expensive to maintain the system and they set out to develop their own simple mail client for computer-ignorant types. Their method was to make the client itself limited and always questioned the user's actions. Starting from Elm's available source code they created a limited program. Today's Pine has the power features as optional instead of non-existent.
Pine uses its own editor instead of giving you the option to use an external one such as vim or emacs. Known as Pico, it's a simplified version of micro emacs which retains similar key bindings but has become one with the E-mail client in terms of seamless power editing. You can obtain Pico as a separate program.
While Pine is free to use (you can read the fine print here: http://www.washington.edu/pine/overview/legal.html), but doesn't fit everyone's definition of "free". In the words of the Pine FAQ on open source, "It depends on how that term is defined. Source for Unix Pine is provided to allow users and system administrators to customize and adapt Pine for their own requirements. UW's Pine license allows anyone to download source code for Unix Pine and make modifications for their own local use without asking permission. Anyone can also create and distribute patch files to implement bug fixes or minor enhancements without asking permission. However, redistribution of a modified version of Pine requires explicit permission from the University of Washington."
Pine is primarily for Linux/Unix, but versions exist for Windows (PC Pine), Amiga, Atari MiNT, BeOS, Mac OS X, VMS and OS/2. It supports SMTP, MIME, IMAP, and NNTP. It does not support the usage of Maildirs or PGP without outside programs or patches. Pine itself is often considered fairly limited, but with patches, extensions and a study of the available options it can be quite powerful. Many people who find Pine to be too limited have switched to Mutt.
Features Include:
Sources:
Personal Experience
"Pine Information Center". University of Washington. 7 Sept. 2004 <http://www.washington.edu/pine/>.