More information is available on the macho common-lisp.net page.
ASDF-install package (obsolete) http://common-lisp.net/project/macho/macho-0.4.tar.gz
macho
Macho is an email web archiving system, similar in scope to pipermail or mhonarc. It generates static html views of an email archive, organized and indexed for easy browsing. It is written entirely in common lisp.