Turn off autosave drafts in mail on OS X El Capitan and Sierra

I am having a bit of an issue here with the default mail application in mac OS El Capitan. I am using my gmail account on the mail client and it is autosaving drafts when I compose messages ... I have done some searching and found various answers saying that I can turn it off by going to Mail --> Preferences --> Accounts and after selecting the account in "Mailbox Behaviours" box just uncheck the "Store draft messages on the server" check box ... as explained in this tutorial that I have found How to Configure Apple Mail to Avoid Duplicate Drafts with Gmail ... But there is a issue ... I don't have that option in my preferences .. please see this screenshot of my preferences screen.

I am really confused on this ... Oh forgot to tell this is my first Mac experience. Looking forward to your answers. Thanks :)

UPDATE: I have upgraded to macOS Sierra ... but the issue still persists ...

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.