Ghost's email guide leans pretty heavily on external services. It doesn't seem to think most people will want to use the server they are running on.

Setting up sendmail on Webfaction is pretty easy, since sendmail is installed on all their boxes. Just put this in your config.js

mail: {  
  transport: 'sendmail',
  fromaddress: '',
  options: {}

There is a weird gotcha here though. This didn't work for me when I left off the options section entirely, and it also failed when I specified the full path to sendmail, as this section encourages you to.