Commenter above has very valid points. I think that with busy people, they're happy to forego etiquette somewhat. My last email went something like this Subje

Commenter above has very valid points. I think that with busy people, they're happy to forego etiquette somewhat. My last email went something like this Subject: One line response needed only Body: Hi X, Could you please tell me what you consider a healthy user activation rate? Thank you Regards --- That's it. Of course, that's not how I would email everyone.