Google announced a couple months ago that it would start calling out sites in mobile results for faulty redirects. This was aimed at saving users the "common annoyance" of tapping a search result only to be redirected to a site's mobile homepage.
This happens when a site isn't properly set up to handle requests from smartphones. As Google noted, it happens so frequently that there are actually comics about it.
Now, webmasters are getting notifications from Google Webmasters Tools indicating when their sites are guilty of this. Here's one Marie Haynes tweeted out:
First time I've seen this. Google sent an email telling a site to stop redirecting its mobile users to the home page pic.twitter.com/DSUn5hA9h4
— Marie Haynes (@Marie_Haynes) August 11, 2014
This was reported on earlier by Search Engine Land, which also reports that Google has added a new color-coded syntax to the Fetch as Google feature within Webmaster Tools, which should make things a little easier at times.
Image via Google