Postfix version 3.1 for RHEL 6/7

The current version of Postfix in the Red Hat repository for RHEL 6 is 2.6.6 release 6.el6_7.1 (November 2015). Presumably this is based on Postfix 2.6.6, which was released in March 2010. According to the change log it looks like there have been very few fixes to the Red Hat version since Postfix 2.6.6 was released.
I need a more recent version of Postfix, ideally 3.1. Is there a Red Hat (or third-party) repo where I can find this? (I've checked the RedHat Software Collections Suite but unfortunately that does not seem to include Postfix: https://access.redhat.com/documentation/en-US/Red_Hat_Software_Collections/2/html/2.2_Release_Notes/index.html)

TIA,
Rob Maidment