Ream-C is a console-based full screen mail client
Lets you access Gmail using low badwidth...
Wrappers around msmtp for use as queueing MTA with extra features
Jnestor is another majordomo in java
Free and open source webmail software
Go Gmailer is a java based desktop app to send emails.
cab
Encrypting E-Mail Client
Business webmail modular application with mobile client
Webmail made easy!
Aspose.Email allows you to work with IMAP, POP and Exchange emails
Roundcube simple captcha plugin