class SomeController extends AbstractController
{
    public function index(
        SendEmailAction $sendEmailAction 
    ) {
        $sendEmailAction->execute(
            new SendEmailRequest(
                'login@domain.zone', //to
                'Greetings!', //subject
                'Hello, it`s me!' // textContent
                '<p>Hello, it`s me!</p>' //htmlContent
            )        
        );
    }
}

Don`t forget

Add parameter app.email.from to config/services.yml. Set email from as a value.