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.
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.
Tine 2.0 is a Web-based groupware solution that focuses on usability and correctness. To achieve these goals, the project uses usability experts and covers most of the code by unit tests. It contains support for contacts, tasks, calendar, email, CRM, VoIP integration, a time tracker, ActiveSync, and a flexible rights management system.
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.
EGroupware is a Web-based groupware suite. It contains many modules, including Calendar (personal calendar and group scheduling, notifications and alarms), Mail (IMAP only), InfoLog (todos, notes, and phone calls linked to contacts/CRM), Contacts (an address book for storing and sharing contact information), ProjectManager, Tracker (bug or incident tracking), TimeSheet, SyncML, CalDAV & CardDAV support, and SiteMgr content management
Zimbra is a next-generation enterprise messaging and collaboration system. It features an Ajax Web client with conversation views, fast email search, Web service mash-ups, shared calendars, document authoring, and IM. The server also syncs to MS Outlook (via MAPI), the Apple desktop (via iSync, iCal, and CalDAV), POP/IMAP clients, and mobile devices (BlackBerry, smart phones, HTML Web browsers). A version of the Web client, Zimbra Desktop, also works offline with any POP/IMAP server. Administrators can control live backup/restores of individual or groups of mailboxes, hierarchical storage (HSM) and clustering, LDAP directory configuration, Web services integration with existing enterprise applications, and integrated anti-spam and anti-virus.
phlyMail is a groupware, webmailer, and PIM. It offers unlimited nested groups, unlimited POP3/IMAP profiles, quotas, an integrated address book, a calendar with multiple reminders and event repetitions, a file manager with an integrated WebDAV server, the ability to send faxes, SMS support (which lets you send SMS, get reminded of events via SMS, and get email notification via SMS), a bookmark manager, themes, and multilingual support. It uses either sendmail or SMTP to send email, and can handle MIME and SSL connections. Support for IDN (Internationalized Domain Names) is included. Through its modular design, it's easy to add completely new features as modules, which can be plugged into the system.
Enigmail is an extension for the mail client of Mozilla, Netscape 7.x, and Mozilla Thunderbird that allows users to access the authentication and encryption features provided by the popular GnuPG software. It can encrypt/sign mail when sending, decrypt/authenticate received mail, and import/export public keys. It supports both the inline PGP format and the PGP/MIME format, which can be used to encrypt attachments, and is cross-platform, although binaries are supplied only for a limited number of platforms. Enigmail uses inter-process communication to execute GPG to carry out encryption/authentication.