Open WebMail is a webmail system based on the Neomail version 1.14 from Ernie Miller. Open WebMail is designed to manage very large mail folder files in a memory efficient way. It also provides a range of features to help users migrate smoothly from Microsoft Outlook to Open WebMail.
phpGroupWare (formerly known as webdistro) is a multi-user groupware suite written in PHP. It provides a Web-based calendar, todo-list, addressbook, email, news headlines, and a file manager. The calendar supports repeating events. The email system supports inline graphics and file attachments. The system as a whole supports user preferences, themes, user permissions, multi-language support, an advanced API, and user groups.
PHProjekt is a modular application for the coordination of group activities and to share informations and document via intranet and internet.
Components of PHProjekt: Group calendar, project management, time card system, file management, contact manager, mail client and 9 other modules
There are two backends for Squirrelmail: the standard backend stores users' profile/preferences in text files (file_prefs.php), and the MySQL one stores them in a MySQL database (file_db.php).
This one adds an LDAP backend. However, things are treated much differently, due to the difference in nature between LDAP and other databases. Namely: LDAP writes are expensive. Extensive caching is used to reduce the overhead on the LDAP server, especially in a setup with a lot of users.
UebiMiau is a simple, yet efficient cross-plataform POP3/IMAP mail reader written in PHP. It's have some many features, such as: Folders, View and Send Attachments, Preferences, Search, Quota Limit, etc. UebiMiau DOES NOT require database or extra PHP modules (--with-imap)
Inside Systems Mail, the first of Inside Systems' projects released as open source, is a webmail system. Programmed in HTML and PHP, it is designed to work with any imap server. ISMail requires that PHP 4.2+, compiled with and IMAP and Session support, be installed on the server that runs it. You have a choice of data-store backends (xml and postgresql are included, each requiring their respective PHP modules), and miscellaneous other options that can make the Inside Systems Mail experience a little friendlier.
Hastymail is yet another webmail IMAP client written in PHP. Hastymail is designed for speed, RFC compatibility, speed, and security. Did I mention speed? HastyMail is intended to be the fastest PHP IMAP client around.
AngleMail began some time ago as the email app for phpGroupWare, and it is the same today. After a year of independant development, and the contributions of a skilled team, AngleMail is again the default email application for phpGroupWare.
NeoMail is a web-based e-mail client that can be installed on any UNIX mail server that is also running a web server. It requires Perl 5, suidperl (included with Perl, or unneeded if you have secure suid script support in your UNIX kernel), and a current version of the CGI and MD5 Perl modules (included with most distributions).
IlohaMail (pronounced: e-lo-ha-mail) is a light weight yet full featured multilingual webmail program that is easy to use and install. It runs on a stock build of PHP, and does not require databases (although database support is available) or the IMAP library (it is powered by a custom IMAP/POP3 library).
Poppawid is a free, fully featured web-based e-mail client written in PHP. Previously, Poppawid was know as Popper-mod_WID, but the name of it has changed to Poppawid. It is an extension of the now abandoned "popper_mod" project which was an extension of the original "popper" project. It runs on any web server that supports PHP and MySQL. It also uses the POP3 mail protocol and SendMail.