Why do you think it's stupid? Here are my reasons for the statement you quoted: 1. It's been years since anyone has emailed me an .rar attachment. In fact, I d

Why do you think it's stupid? Here are my reasons for the statement you quoted: 1. It's been years since anyone has emailed me an .rar attachment. In fact, I don't think I've had a legitimate .rar file in my Inbox since the turn of the millennium. 2. The last time I regularly opened .rar files was when I was into warez. Those things often contained malware. 3. As a result of 1) and 2), I would be very suspicious if somebody sent me an .rar file. Of course, that's just my perception, so other people might associate the .rar extension with better things.