SharpWebMail

SharpWebMail is an ASP.NET webmail application that is written in C#. It uses a POP3 or IMAP servers as the mailstore and sends mail through a SMTP server. It is very simple to configure (only a few settings in the web.config file). You can compose HTML messages, search your inbox, read complex mime messages, have multiple address books and much more.
Currently it fully works under:
- Microsoft .NET framework 1.1
- Microsoft .NET framework 2.0
- Mono 1.1
- Mono 2.0

Go to http://anmar.eu.org/projects/sharpwebmail/

See also these related projects.