Hey guys,

I recently noticed that in subject lines in Gmail strange icons starting to appear. I haven't seen these types before: http://prntscr.com/6fg1yl

I haven't seen these before. Unbounce is using it pretty cleverly for webinars. But how are they doing it?
By looking at the source code these are "goomoji"s but I have no idea how these work.

Anyone can enlighten me?