Android send SMTP email programmatically: 1)simple java package , 2)using accessibility service

This is for my hobby, is not for commercial use. I need an example that works because I have not been able to figure it out myself. Pleas use Android Studio for 5.1 Lollipop. Keep it simple. Lots of logcat for debugging, and code comments are good. 1. Make a SIMPLE package to send email on background thread by pressing a single button. Just hard code the gmail address, from, to , body, etc. You can get a new gmail address for the example, or use one of mine, which I will send you with password, and is set to allow less secure apps. 2. Make a similar SIMPLE package that uses the built-in gmail API via an accessibility service for filling out the form fields and pressing the buttons. That is, when finished, just press the single button and the code automatically populates the gmail form and presses the send button. This is not for outside use. I need a code example to help me understand accessibility service. Im having trouble learning this. Thank you for your time considering this.