Ironic or shameless or whatever, this goes against Adsense TOS: you cannot promote a service of theirs (here: Gmail) and explain how to hack that service.

I was recently "kindly" asked by Google(had 48 hours to comply) to remove Adsense from a innocuous post on my blog because said post was just a couple lines explaining how I used some online service to download a video from Youtube (which, apparently, hurts their TOS and feelings)