Binc IMAP is a GPL licensed IMAP4rev1 server for Maildir, written in C++. 
It strives to be stable, fast, flexible, and RFC compliant.

For those familiar with qmail-pop3d, this IMAP server will be the natural
choice. It is invoked similarily and uses checkpassword to authenticate. 

WWW:	http://www.bincimap.org/