It displays each mailbox and message in a separate window, thereby allowing one to simultaneously open as many mailboxes and view and compose as many messages as one wishes.

A GNOME email client, supports POP3 and IMAP4.

Exmh is an X user interface for MH mail using Tcl/Tk.

GNUMail.app is a clone of NEXTSTEP's excellent Mail.app application. It uses the GNUstep framework and runs on many Unix versions and under MacOS-X.

A tool for reading, composing, organizing, and filing electronic mail. Built with OSF/Motif, supports CDE. Thirty day evaluation period.

A user-friendly mail client for The X Windows System, drawing inspiration from mail clients such as Qualcomm's Eudora amongst others.

A clone of the NeXT Mail.app for the X Windows system.

Themeable, GTK-based mail client written in Perl. Supports POP3, display of HTML mail.

Tcl/Tk mail client, also known as TkRat.

Sandmail is a user mail agent being written for the XFree86 with the GTK+ widget set, in C.

Mail client written with the Gtk+ widget set. Supports POP3 and IMAP.

GTK+ based e-mail client for XWindows.

Althea is an IMAP client for X Windows that uses the GTK widget set. It allows an almost unlimited number of servers, and has a very small memory footprint.

v2.0 is an X windows interface to reading mail built using Tcl/Tk and Perl.

A full-featured e-mail client with support for SMTP, POP3, basic IMAP, and LDAP support for a global address book.

XCmail is a MIME and POP3 capable mailtool for X11 using the Xclasses layout library.