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.
kmMail is a PHP-based mail program, based on the mail functionality of Keftamail and is being developed by current Kefta employees. It is meant to be a framework for putting a web-based mail program on your site, but is still robust enough to drop into your current site with little to no modification. The goals of kmMail are MIME compliance, speed, low overhead, and an enjoyable user interface.
Mail::Cclient is a Perl module and gives access to mailboxes in many different formats (including remote IMAP folders) via the c-client API. The c-client library is the core library used by Pine and the University of Washington IMAP daemon (written by Mark Crispin). Sort, search, threading, and the SMTP API are supported.
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.
IP*Works! is a comprehensive suite of more than 40 native Linux class libraries for Internet development. It is a robust framework of enterprise-class tools, enabling rapid integration of any major Internet protocol or technology, including FTP, HTTP, SMTP, POP, IMAP, SNMP, LDAP, DNS, RSS, SMPP(SMS), XMPP (Jabber), SOAP, and WebDav. It includes source code for compilation on various Unix platforms, a framework for Objective-C (Cocoa) Mac OS X development, and native PHP extensions.
IP*Works! SSL adds SSL security, digital certificate generation, and certificate management capabilities to the base IP*Works! Linux class libraries. It supports secure implementations of every major SSL- enabled Internet protocol, including FTPS, HTTPS, SMTPS, POPS, IMAPS, LDAPS, SMPPS, XMPPS (Secure Jabber), SOAPS, and WebDavS.
Ristretto is the mail API that is used by Columba, a Java mail client (http://columba.sf.net). It is available as a stand-alone API, and it provides a well-tested, slim, and fast Java implementation of all relevant mail protocols and features. It is licensed under a MPL/LGPL/GPL tri-license.