List of freely available Mail clients
| Name | Lang | Comments |
| Adora | Tcl/Tk | Supports MBOX and POP3. No more developed. |
| Aethera | C++ (KDE) | Based on the Magellan source. Should be KDE's Outlook/Evolution. |
| Alpine | C (c-client) | Alpine is a fast, easy to use email client that is suitable for both the inexperienced email user as well as for the most demanding of power users. Alpine is based on the Pine Message System. |
| Althea | C (GTK+) | IMAP only; very simple. |
| Animail | Python | |
| Arrow | C++ (JX) | Displays each mailbox and message in a separate window. MBOX and POP only. |
| Balsa | C (Gnome) | Supports mbox, maildir, mh, POP3 and IMAP. Uses libmutt as backend. Supports different encodings. |
| Claws Mail | C (GTK+) | Lightweight, and fast e-mail client. Supports MBOX, MH, POP3 and IMAP. (Was) based on Sylpheed. |
| CMC | Perl/GTK+ | |
| Cone | C | Cone is a text-based mail client and a simple newsreader. |
| Cronos II | C (Gnome) | Uses its very own database storage format. |
| elm | elm is one of the most common mail readers for unix. | |
| Evolution | C (Gnome) | Should be Gnome's Outlook. Supports VFolders. Supports different encodings. |
| Exmh | Tcl/Tk | Exmh is an X user interface for MH mail. |
| Ezimail | C (Curses) | Ezimail is a port of the Carnegie Mellon AMS client ezmail modified to use IMAP. It is a text-based client and supports strong authentication. |
| GNUMail | Objective-C (GNUstep) | Supports SMTP, POP3, IMAP, mbox. |
| gtkmail | C++ (gtk--) | |
| Ishmail | C++ (Motif) | Until recently, it was a commercial flagship product developed by HAL Computer Systems (then H&L Software). Now it's GPLed. Messages are opened in separate windows. Supports different encodings. |
| Kiltdown | C++ (Qt) | Currently supports only POP3 and mail spool files. |
| KMail | C++ (KDE) | |
| Mahogany | C++ (c-client, wxWidgets) | It is very cofigurable, supports mbox, mh, pop3 and imap, has filters, supports multiple encodings, has multiple identities, can be scripted and extended thanks to a builtin Python interpreter and has PalmOS connectivity. |
| MMC | C++ (Gnome) | |
| MMR | C++ | MMR is a very simple mailer written as an alternative to PINE. It's not very fancy, but it handles message threading and MIME attachments. |
| Mulberry | C++ (JX) | Displays each mailbox and message in a separate window. Supports MBOX, POP3 and IMAP. It was commercial, now open source. |
| Mutt | C | Small but very powerful text-based MIME mail client. It is highly configurable. |
| nmh | nmh (new MH) is a powerful electronic mail handling system. It was originally based on version 6.8.3 of the MH message system. | |
| Pine | C (c-client) | ne is no longer under active development. Consider evaluating its successor, Alpine, which supports all of Pine's functionality and more. |
| Postilion | C, Tcl/Tk | Postilion is a mail user agent based upon the popular TkRat program. The main changes to TkRat are in the user interface portion. It looks like NeXT Mail.app and it's best when compiled and run with TkStep8.0.4 instead of the regular Tk. It REQUIRES Tcl/Tk 8.0p2 and because of that it does not support multiple encodings which were introduced only in Tcl/Tk 8.1. |
| Pronto! | Perl/GTK+ | Supports mbox, maildir and POP3, can use database supported by Perl DBI interface as the backend. Supports Vfolders. Pronto is continuation of CSCMail after CSCMail moved to C. |
| Pygmy | Python (Gnome) | Only supports the Unix mailbox format. |
| rzMail | Python (wxPython) | |
| SQmaiL | Python (Gnome) | Uses mySQL for message storage. |
| Spruce | C (GTK+) | Supports mbox, POP3 and IMAP. |
| Sylpheed | C (GTK+) | Lightweight, and fast e-mail client. Supports MBOX, MH, POP3 and IMAP. Supports multiple encodings using jconv. |
| Thunderbird | C++ | Mozilla's Thunderbird 2 email application. |
| TkRat | C, Tcl/Tk | It is mainly written in C but the user interface is done in tcl/tk. Supports MIME, multiple encodings, Virtual folders, PGP support, unix mail files, MH folders, POP3 and IMAP. |
| TradeClient | C (c-client, GTK+) | Uses Mahogany patch for c-client. TradeClient is an LGPL'd subset of Bynari's TradeXCH client. It has support for a personal calendar, MBOX, POP3, IMAP. |
| (X)Emacs/VM | VM is a mail reader written in Emacs LISP for GNU Emacs and XEmacs. It supports local spool files, POP3 and IMAP, vfolders. | |
| (X)Emacs/Gnus | Gnus, the Emacs newsreader. | |
| (X)Emacs/Mew | Mew is a mail reader for Emacs. | |
| XCmail | C++ (Xclasses) | Supports mbox and POP3, has helpers, filters, PGP support. |
| XFMail, mirror | C (XForms) | Supports MBOX, MH, POP3, IMAP, multiple encodings. |