Mail ConfiGuru is a standalone cross-platform tool and library that displays the configuration of email clients available to the currently logged-in user. It provides one interface to the settings of all supported email clients, which currently includes Mozilla Thunderbird, Mozilla Mail (SeaMonkey), MS Outlook, MS Outlook Express, KMail, and Ximian Evolution.
Roundcube Webmail is a browser-based, multilingual IMAP client with an application-like user interface. It provides the full functionality you expect from an email client, including MIME support, address book, and folder manipulation. High extensibility is granted by the plugin API and the user interface is fully skinnable using XHTML and CSS 2.
Claws Mail is a GTK+ based, lightweight, and fast email client. Almost all commands are accessible with the keyboard. It also has many features such as multiple accounts, POP3/SMTP/IMAP/NNTP support, OpenSSL, GnuPG, and LDAP support, a plugin system, spell checking, filtering, Actions, spam and virus filters, an address book, internationalization, and much more.
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.
Zoho Virtual Office provides a virtual collaboration platform with which individuals and groups can communicate, collaborate, organize, and share information seamlessly. The collaboration suite includes email, documents, calendar, tasks, contacts, notes, links, IM, and more. Zoho Virtual Office allows users to create multiple groups and provides smooth collaboration of these components within groups. All data in the system can be accessed from any computer that has an Internet connection and a Web browser.
xbmcmail-imap is an IMAP/IMAPS email reader for the XBox using the XBox Media Center's builtin Python engine. It supports attachments, folders, mail management (copy, move, delete), printing (text or postscript), multiple accounts, background polling, RTF and HTML converters, and more.
PigeonReader is the Web mail client of the PigeonAir project, a solution for easily building clustered, scalable, and modular email services. PigeonReader is completely UTF-8 compliant, allowing any charset to be used. It is based on XML, which allows skins and themes to be easily written using the XSLT language. It was written to be easily used in a cluster of Web servers, where multiple and different domains are to be managed transparently to the end user, possibly with different skins, features, and configurations.
DisSent (short for "Distribute Sent Mails") is a program for separating your sent mail from a single folder into different folders based on properties of the individual messages in the folder. It scans your mail storage and proposes a set of actions to tidy up your sent mail folders. More precisely, it gives you a list of messages along with proposals on where to move these messages. You can then select the messages you want to move and let DisSent do the actual work.