We do a lot of email marketing and sometimes developers will put the html file out on the image server (i know the easy answer is to not do this) but those html files end up getting indexed by Google and eventually rank high on search results. Which in turns makes the SEO company's want us to remove these pages. Is it possible to have google not index anything from our sub domain? we have image.{ourUrl}.com where we put all these files.
Would putting a robot.txt file in the main directory do it? Or would we need to add that robot text file in every directory?
Is there an easy way to blanket this?
A robots.txt file would just stop crawling, files might still be indexed. a noindex directive would work, you could use an x-robots-tag. See here https://developers.google.com/webmasters/control-crawl-index/docs/robots_meta_tag