Answer by Rishita Joshi for Sending Email in Android using JavaMail API without using the default/built-in app

package io.formics.tourguideimport android.annotation.SuppressLintimport android.content.Intentimport android.net.Credentialsimport android.net.Uriimport androidx.appcompat.app.AppCompatActivityimport android.os.Bundleimport android.util.Logimport android.widget.Toastimport kotlinx.android.synthetic.main.activity_feedback.*import org.jetbrains.annotations.Asyncimport java.lang.Exceptionimport java.util.Properties;import javax.activation.DataHandler;import javax.activation.FileDataSourceimport javax.mail.*import javax.mail.internet.*class FeedbackActivity : AppCompatActivity()  {    val props = Properties()    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_feedback)        props.put("mail.smtp.auth", "true");        props.put("mail.smtp.starttls.enable", "true");        props.put("mail.smtp.host", "smtp.gmail.com");        props.put("mail.smtp.port", "587");        btnSendEmail.setOnClickListener {            Thread {                try {                    sendEmail()                    // Your implementation                } catch (ex: Exception) {                    ex.printStackTrace()                }            }.start()        }    }    private fun sendEmail() {        try {            val session = Session.getInstance(props,                object : javax.mail.Authenticator() {                    //Authenticating the password                    override fun getPasswordAuthentication(): javax.mail.PasswordAuthentication {                        return PasswordAuthentication("abc@xyz.com", "password")                    }                })            val message = MimeMessage(session);            message.setFrom(InternetAddress("abc@xyz.com"));            message.setRecipients(                Message.RecipientType.TO,                InternetAddress.parse(editCC.text.toString())            )            message.subject = editSubject.text.toString()            message.setText("Dear Mail Crawler,"+"\n\n No spam to my email, please!"            );            //val messageBodyPart = MimeBodyPart();            //val multipart = MimeMultipart();            //val file = "path of file to be attached";//            val fileName = "attachmentName"           // val source = FileDataSource(file);            //messageBodyPart.setDataHandler(DataHandler(source));            //messageBodyPart.setFileName(fileName);            //multipart.addBodyPart(messageBodyPart);            //message.setContent(multipart);            Transport.send(message);            System.out.println("Done");        } catch (e: MessagingException) {            throw  RuntimeException(e);        }           }}