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.
getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
imapbiff is a small perl/tk program that notifies you of new mail in an IMAP mail account. It only checks IMAP accounts, not local mail files or POP accounts. When you do not have any unread messages in your IMAP Inbox, it will display a mailbox icon with the flag lowered. When it detects new messages in your IMAP Inbox, it will beep and raise the flag. Whenever it is querying the IMAP server, a "?" is displayed to indicate that it is checking for messages.