Dear all,
There's a detailed article about iRedMail in the latest issue of
BSD Magazine: Deploy a Full-featured Mail Server on OpenBSD 5.1
with iRedMail.
Summary of other articles in this issue is available here:
http://bsdmag.org/magazine/1806-kerberos-on-openbsd
If you're interesting in this detailed article and/or BSD Magazine,
it's free to download a PDF edition: http://bsdmag.org/
Enjoy. 