Turn off autosave drafts in mail on OS X El Capitan and Sierra
After no one replied so I did some research on this again ... though I could not find how to turn off the autosave draft feature on my apple mail application ... I did figure out a way to deal with this annoying drafts problem ... All I did is that in "Mailbox Behaviors" tab I changed the location of the Drafts folder ... now instead of saving the drafts in Gmail/Drafts folder the mail application is saving them in a Local Drafts folder on my mac ... Life is much easier now ... now I don't have to see all those drafts when I open my mailbox on my smartphone.