sTeam provides a technical platform which allows groups of students, lecturers, and any other groups to construct and arrange their individual and cooperative learning and working space. It consists of an object-oriented server connected to a database, and Web, Java, and other (FTP, SMTP, IRC, etc.) clients. The server is event-driven and manages all user objects as well as the communication between the connected clients. Features that were different from most other cooperation tools is the self-organisation and self-administration by the members within the virtual environment.
Decimail Server is a mail server supporting IMAP and SMTP that uses a PostgreSQL database to store messages. Mailboxes are defined using SQL queries, allowing complex client-independent automatic message filtering and categorisation. For example you can partition your messages chronologically, by correspondent, and by mailing list at the same time, with each message appearing in several mailboxes. You can also use PostgreSQL's text indexing extension for fast keyword searching. Decimail also features anti-spam processing of outgoing messages.
IMAPEngine is an IMAP server that uses a tdbengine database structure to store all accounts, messages, and mailboxes. This means it has nearly no limits in numbers, sizes, and performance, and it uses indexes to sort/find its data. IMAPEngine is IMAP4Rev1 compatible and also has built-in support for the ACL, ID, IDLE, and UIDPLUS extensions. It is not (yet) an MTA, but it retrieves incoming messages from different POP3 servers. An simple integrated Web interface makes account configuration easy.
AtMail is a webmail client. The project aims to provide an elegant client for existing IMAP mailservers, with less bloat and a focus on an intuitive, simple user interface. Features include complete Webmail functionality, address-book support, video mail, an AJAX interface, drag'n'drop, and more.