Package should depend on bsd-mailx, mailx or mailutils and module must be set to use /usr/bin/mail instead of /bin/mail. According to packages.debian.org, there is no /bin/mail in etch/lenny/sid
See http://packages.debian.org/search?searchon=contents&keywords=%2Fbin%2Fmail&mode=path&suite=stable&arch=any -- Tomas
