KMail is the default mail client for the KDE desktop environment for *nix-based computers. Over the years it has evolved from a barebones but usable mail client to a full-featured and comprehensive replacement for Outlook Express or Eudora. It has hooks into the rest of the KDE environment for address book, encryption, and calendaring features, and with upcoming releases will be used as a component in the Kontact integrated PIM.
KMail was one of the first KDE applications to be developed. An early KMail page at http://www.geocities.com/SiliconValley/6702/kmail.html shows an alpha snapshot dated 97/05/25. It was complete enough to have been included in KDE 1.0, released in July 1998, and has been included in every KDE release since then. Development of KMail was strong through KDE 1.x and, like everything else in KDE, was overhauled considerably for KDE 2.0. Versions 2.1 and 2.2 refined this, the most significant improvement being the addition of IMAP support in 2.2. KDE 3.0 was accompanied by another evolutionary KMail release, as were KDE 3.1 and KDE 3.2.
The main KMail interface will be familiar to anyone who has used Netscape/Mozilla Mail/Mozilla Thunderbird. Three panes are displayed, one for folders, one for messages, and one for message content. Support for large numbers of email folders is available, and there is a built-in, configurable filtering system that allows mail to be redirected to the appropriate folders. The message composer is based on the text editor component used throughout KDE and has spell-checking, an interface to PGP/GPG, and integration with KAddressBook. There is also a simple but versatile queuing system for intermittent connections that I have never used. Messages are stored in the well-known and compatible Maildir format, and there are many tools available for converting mail from other formats, including the older mbox format used by Netscape/Mozilla and Eudora, as well as just about every console mail client in the history of Unix.
KMail remains one of the more prominent GUI mail clients for *nix systems. It has a long development history, is fast, compatible, and stable, and integrates well with the rest of KDE. I have used it as my primary mail client for about three years without incident. If you're looking for a simple GUI mail client for a Linux/Unix system, and don't mind the weight of KDE, KMail is a good choice.
The KMail homepage at http://kmail.kde.org/ was a major source for this writeup.
This writeup is copyright 2003 D.G. Roberge and is released under the Creative Commons Attribution-NonCommercial-ShareAlike licence. Details can be found at http://creativecommons.org/licenses/by-nc-sa/2.0/ .