Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
Postfix Admin - Postfix Admin is a web based interface used to manage mailboxes, virtual domains and aliases.
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.
VBox.Adm - VBoxAdm is web frontend written for mailservers running with Postfix, Dovecot and a MySQL backend.
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
ViMbAdmin - ViMbAdmin (pronounced vim-be-admin and meaning Virtual Mailbox Administration) is intended as an...