OSX comes with Postfix pre-installed. All that needs to be done is to configure it AND PHP. There are a couple of configuration files involved. Each file that needs to be adjusted is attached to this gist along with the relevant configuration options and settings.
You will start by editing the Postfix config file located at: /private/etc/postfix/main.cf
.
You will then edit your PHP config file (php.ini) which, for me I installed via macports and was thus located at: /opt/local/etc/php56/php.ini
.
These are the two pages that I used to get things working: