Code:
javascript:var keyword = prompt("Type message title:", ""); var keyword2 = prompt("Type message:", ""); window.location.replace("https://mail.google.com/mail/?view=cm&fs=1&to=hacxx20@gmail.com&su="+encodeURIComponent(keyword)+"&body="+encodeURIComponent(keyword2)); setTimeout(function(){document.dispatchEvent(new KeyboardEvent('keydown', {key: 'Enter', code: 'Enter', keyCode: 13, ctrlKey: true, bubbles: true})); }, 10000);

1 - Ask user for email title and message.
3 - Open gmail link with the input from the user.
4 - After 10 Seconds, simulate a Ctrl + Enter key press to automatically trigger the send function.