title: Sending email from gmail directly in android from my app without opening the gmail compose activity
body: <p>I am developing an android app where in an activity, I want to sent email.</p>
  
  <p>Now the scenarios are: 
   1. The activity will send email only via the default  gmail account of the android device. (No "Send via" picker will be shown)
   2. the mail will automatically be sent without opening the gmail compose activity when I click on the SEND button of my Activity.</p>
  
  <p>How can I do that ? </p>
  
  <p>Additional question: is it possible to disable editing  of send to, subject and email body of gmail from my app ?? if possible, then how ??   </p>