Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
Kolab is a groupware system that provides a comprehensive and flexible solution for workgroups. Email, contacts, and group calendars can be managed via the Web, Windows/Outlook, and Linux/KDE. It supports offline synchronization and full seamless support of mixed client environments because the Kolab-XML storage format is fully open and avoids MAPI/TNEF.
UnDBX is a tool to extract, recover, and undelete email messages from Outlook Express .dbx files. On first run, all messages are extracted as individual .eml files. Subsequent runs only update the output directory with new messages, and delete old .eml files that correspond to deleted messages in the .dbx file. Corrupted .dbx files (including files larger than 2GB) can be opened in recovery mode, in order to recover messages and partially undelete deleted messages. The success of recovery depends on the type and level of .dbx file corruption.
Jaro Mail is an integrated suite of interoperable tools for GNU/Linux and Apple/OS X to manage email communication in a private way, without relying on online services (in fact, encouraging users to store email locally). It mainly features a system for mailinglist filtering, address-book integrated whitelisting, and long-term email storage and archiving with functions for fast search and usage statistics. It makes internal use of customized versions of popular Unix tools like Mutt, Fetchmail, Procmail, Mairix, and Msmtp.