Atmail is a fully-featured email server and Webmail client, allowing users to send and receive email via a Web browser or mobile device. It has full support for IMAP mailboxes, and an optional email-server mode that uses EXIM as the MTA. Features include a scheduler, MySQL backend support, spell-check, address book, calendar user preferences, multiple accounts, SpamAssassin support, migration scripts from other mail servers, a customizable interface, an attractive AJAX interface, an optional group sharing Calendar/Addressbook, and an Outlook plugin to sync Contacts/Tasks/Calendar data between a Desktop, Mobile, and Webmail client or other email users.
The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
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.
Dolda Webmail (or d-mail for short) is a Webmail system written in PHP and interfacing with a back-end IMAP server. Advantages over most other projects of a similar sort are that it uses a persistant connection to the IMAP server (which increases performance on the Web server, reduces load on the network and on the IMAP server, and doesn't force the Web server to store the user's password in-core), and that it makes full use of XHTML 1.1 and CSS 2.
Simple Groupware is a complete enterprise application offering email, calendaring, contacts, tasks, document management, synchronization with cell phones and Outlook, full-text search, and much more. Simple Groupware combines standards like RSS, iCalendar, vCard, IMAP, POP3, SMTP, CIFS, CSV, WebDAV, LDAP, and SyncML under one platform. Unlike other groupware software, Simple Groupware contains the programming language sgsML to enable the quick customization and creation of powerful Web applications.
ezmlm-idx is an addition and patch to ezmlm, adding multi-message threaded archive retrieval, digests, remote administration, message and subscription moderation, subscriber-only restrictions, message trailer, subject prefix, subscriber name storage, customizable setup, multi-language and MIME support, and more. In addition, it has improved bounce handling, case-insensitive subscriber address storage, and support for distributed lists (main and sublist are transparent to the subscriber). It can be compiled with MySQL or PostgreSQL support.