Still no plan to support OpenBSD, sorry.
I'd like to tell you a long story if you don't mind if i blabla here:
I'd like to say, I'm a big fan of OpenBSD, i purchased and resold official CD and T-Shirts in China mainland in 2006 and 2007, it IS my favourite OS. To help promote OpenBSD, i want to start with developing some server solutions based on OpenBSD which might be needed by enterprises, and i chose to start with a mail server solution. That's why iRedMail born (it was named "OMS" in the beginning, which means "OpenBSD Mail Server"), and it was made for OpenBSD only in the beginning (Nov 2007). Due to lack of OpenBSD users in China mainland, i ported it to RHEL/CentOS in 2008, hope it will attract more users. But OpenBSD support was deprecated in later 2008. OMS project was a failure because it had only Chinese documents, although shell scripts and source commit logs were all commented in English.
Well, you see, how conflicting i am. I love it but i didn't do some more for it, like making iRedMail work on it. Actually, i registered a Google Code project here: Puffy Mail, just don't have enough time to start it. (well, an excuse, lazy man.)
Currently, OpenBSD has most of all mail server related components, for example:
Apache-1.3.x, with chroot enabled by default. But it will be replaced by Nginx in next release.
OpenSMTPD(8): SMTP daemon.
ldapd(8): LDAP server. Just a quick note, iRedMail LDAP schema file and iRedAdmin-Pro (OpenLDAP edition) works perfectly with ldapd, i tested it before.
spamd(8): grey/white/blacklisting, with builtin PF integration.
relayd(8): relay daemon, useful for server load-balance. I simply tested it with another friend in 2007, it was named "hoststated" in the early stage.
PF + pfsync for firewall and fail-over.
It should be easy to make iRedMail work on OpenBSD, but i just didn't try it.
iRedMail now supports many Linux/BSD distributions, i have to spend many time to test it for new features and stability before releasing a new version, so i need someone to help test it if we want to make it work on a new distribution.