Hello,
I have worked with qmail-ldap and Dovecot for a number of years, and recently wrote up a piece going into great detail about all aspects of our environment. It currently supports a rather small installation of ~10K active users. If it should be of interest:
http://fritz.potsdam.edu/projects/email
It is intended primarily for system administrators or mail administrators interested in building mail infrastructure on top of open-source technologies, and is inspired by the likes of Life with qmail.
Topics include storage, backup, directory integration, local and remote mail exchange, checkpassword SMTP-Auth and Dovecot login, RBLs, content-scanning and anti-spam, quarantine, webmail, etc. Full installation directions and configuration stanzas are provided for nearly every piece of the infrastructure.
Comments/criticism welcome. Cheers.
-Jeff
-- Jeffrey M Hardy Network / Systems Administrator hardyjm@potsdam.edu