Last time I was buying Gmail ads, they let us put an ad in the promotions tab of the inbox which looked like an email. It was something they were testing at th

Last time I was buying Gmail ads, they let us put an ad in the promotions tab of the inbox which looked like an email. It was something they were testing at the time, but it was reasonably effective and I imagine it is still around. The old gmail sidebar ads were absolutely worthless. Roughly 0.05 clicks per 1000 impressions, and those clicks were mostly accidental. They removed those ads because they were worthless to anyone.