The Darwin Calendar Server is a standards-compliant server that allows multiple users to collaboratively share calendaring information. It provides a shared location on the network to store schedules, and allows users to send each other and manage invitations. In order to provide interoperability with multiple calendaring clients, the server implements the CalDAV protocol, which is an extension of WebDAV, which is in turn an extension of HTTP.
Apache SpamAssassin is an extensible email filter that is used to identify spam. Once identified, the mail can then be optionally tagged as spam for later filtering. It provides a command line tool to perform filtering, a client-server system to filter large volumes of mail, and Mail::SpamAssassin, a set of Perl modules allowing Apache SpamAssassin to be used in a wide variety of email systems.
The Netty project is an effort to provide an asynchronous, event-driven network application framework and tools for rapid development of maintainable, high-performance, high-scalability protocol servers and clients. In other words, Netty is a NIO client server framework that enables quick and easy development of network applications such as protocol servers and clients. It simplifies and streamlines network programming such as TCP and UDP socket servers.
SubEthaSMTP is an easy to understand Java library that provides a receptive SMTP server component. By plugging this component into your Java application, you can easily receive SMTP mail using a simple abstract Java interface. Also included is a small sub-project called Wiser, an easy to use incoming mail testing framework.
OpenDMTP (Open Device Monitoring and Tracking Protocol) is a highly configurable and extensible protocol for communicating with mobile devices over high-latency/low-bandwidth networks. The protocol is particularly geared towards the transmission of GPS base location information and includes a full-featured reference implementation showcasing its capabilities.
Echomine Feridian is an easy-to-use Java API that gives you quick and easy access to the XMPP network used in IM services such as Google Talk. The API allows you to communicate with Jabber/XMPP servers for sending and receiving instant messages, presence management, and custom extensions to the XMPP protocol.
GreenMail is a suite of email servers for testing purposes and sandbox development. It supports SMTP, POP3, and IMAP (including SSL) and can be embedded into any Java application or unit test. The GreenMail Service (SAR) extension runs as a JBoss embedded developer mail server sandbox, manageable via JMX.