BrowserExpress is a Web-based e-mail client. BrowserExpress provides a Web browser interface to any mail server, giving all your users Web-based e-mail from any Web browser. The BrowserExpress interface is fully customizable to support your branding, banner advertisements, and language choice. BrowserExpress implements POP3, SMTP, LDAP, and MIME standards.
Citadel is an advanced messaging and collaboration system for groupware and BBS applications. Users can connect to Citadel using any telnet, WWW, or client software. Among the features supported are public and private message bases (rooms), electronic mail, real-time chat, paging, shared calendaring, address books, mailing lists, and more. Unlike other collaboration servers, Citadel provides its own data stores and is therefore extremely easy to install; you don't have to "bring your own" email and database because they're built in. The server is multithreaded and scalable. In addition, SMTP, IMAP, and POP3 servers are built-in for easy connection to Internet mail. Citadel is both robust and mature; it has been in production since 1987.
The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols such as ESMTP, IMAP, POP3, LDAP, SSL, and HTTP. Courier provides ESMTP, IMAP, POP3, Webmail, and mailing list services within a single consistent framework. Individual components can be enabled or disabled at will. Courier implements basic Web-based calendaring and scheduling services integrated in the Webmail module.
Courier-IMAP is a lightweight server that provides IMAP access to maildir mailboxes. It supports folders, custom authentication modules, and virtual mailboxes. A compatible POP3 server is also provided. The source code is based on the IMAP module in the Courier Mail Server, but this build is independently repackaged to work with any other MTA that delivers to maildir format mailboxes.
The Cyrus IMAP server is generally intended to be run on sealed systems, where normal users are not permitted to log in. The mailbox database is stored in parts of the filesystem that are private to Cyrus. All user access to mail is through the IMAP, POP3, or KPOP protocols. The private mailbox database design gives the server large advantages in efficiency, scalability, and administratability. Multiple concurrent read/write connections to the same mailbox are permitted. The server supports access control lists on mailboxes and storage quotas on mailbox hierarchies, multiple SASL mechanisms, and the Sieve mail filtering language.
The DBMAIL package replaces the normal UNIX mailing system. All email and user data is stored in a database. You can create an unlimited number of email accounts, which can be checked using the POP3 or IMAP protocol. Users can maintain their own set of email addresses. It is more scalable, more secure, and faster than traditional mail systems. DBMAIL has storage drivers for PostgreSQL and MySQL, and it has authentication drivers for PostgreSQL, MySQL, and LDAP.