Java program that creates an SMTP message and sends it off. It can be used to test SMTP functionality as well as security. This test SMTP at the application level. Requires Java 6.
MGTalk - Jabber client for j2me midp 2.0 platform, supports some Google Talk server features. May run on any j2me midp 2.0 mobile phone or communicator. MGTalk is not affiliated with Google in any way
MrPostman is an email gateway from local POP clients like Microsoft Outlook, Mozilla's mail client etc. to different web mail services like Yahoo and Hotmail.
It is being designed for extensibility so is easy to add more web mail services to it.
An email client written in Java, C, and C++ which not only allows standard pop/smpt/imap access, but also integrated access to Yahoo!, Hotmail, Lycos, and many others. This is all done without any additional services (such as pop forwarding).