IMP 3 is the new stable version of IMP. Features that have been added
include searching; a new, flexible preferences system; a hierarchical
folder tree; and more.

It requires PHP4. You should use it if you want to take advantage
of PHP4s built-in session handling and improved speed or if you
want access to features such as the interactive spell checker and
folder searching.  PHP4 should be configured to support IMAP /
IMAP-SSL, OpenLDAP, OpenSSL, mcrypt, XML, FTP, gettext, zlib, MCAL
and a database (like MySQL or PostgreSQL). For Japanese language,
please enable mbstring.

WWW: http://www.horde.org/imp/