postfix 3.0.3 is now available for OpenIndiana Hipster, compiled on entire@@0.5.11-2015.0.1.1.
(I've added dovecot@2.2.21 as well)

The symbolik links to get e.g. /usr/lib/sendmail are now *mediated*, that means, they might by default point to files from the OS-Distro "mailwrapper" or classic "sendmail" only optionally to this SFE postfix package's files.