When setting up mail servers in the past, the longest part has always been creating the configuration files for each of the services. I had a look around for a script, but could only find ones for Debian, so I decided to take one of them and convert it for Centos 6. I prefer running Centos because of how long the support for it is, which then makes there be less chance of any updates breaking the server. There are probably still some bugs in the script, but it is finally at a stage where it can successfully set up the services on a Centos 6 minimal install.
The script is at: