Mahogany is an OpenSource(TM) cross-platform mail and news client.  It is
available for X11/Unix and MS Windows platforms, supporting a wide range of
protocols and standards, including POP3, IMAP and full MIME support.  Thanks
to its built-in Python interpreter it can be extended far beyond its original
functionality.

Mahogany's wealth of features and ease of use make it one of the most powerful
clients available, providing a consistent and intuitive interface across all
supported platforms.

Mahogany is being developed using the free wxWindows application framework,
building on the gtk toolkit on Unix. 

WWW: http://mahogany.sourceforge.net/