Issue sending html email with images in php

I have two HTML templates. And I buffer them into php email using ob_start() and ob_get_clean(). However, one can be sent without any problem while another has no images in the email body. Can anyone find what the problems are? Here are the two templates:

• the good one: http://www.emoceanstudios.com.au/good.txt
• the bad one: http://www.emoceanstudios.com.au/bad.txt

I have tried to use absolute path for images, and tried to use img tag instead of div with background image, but they don't work.