" javax.mail.AuthenticationFailedException ~" Using SMTP on Android

Question

I want to send Authenticate code(randomly generated) by using SMTP on Android. But, I have a problem

This is my error

https://i.stack.imgur.com/W5XLZ.png

Do you have any solution about my problem?

Here's my source code

 class GmailSender : Authenticator() {

      private val fromEmail = R.string.manager_email.toString()
      private val password = R.string.manager_email_pw.toString()


     fun sendEmail(toEmail: String) {
            CoroutineScope(Dispatchers.IO).launch {
                 val props = Properties()
                 props.setProperty("mail.transport.protocol", "smtp")
                 props.setProperty("mail.host", "smtp.gmail.com")
                 props.put("mail.smtp.auth", "true")
                 props.put("mail.smtp.port", "465")
                 props.put("mail.smtp.socketFactory.port", "465")
                 props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory")
                 props.put("mail.smtp.socketFactory.fallback", "false")
                 props.setProperty("mail.smtp.quitwait", "false")

                 val session = Session.getDefaultInstance(props, this@GmailSender)
                 val message = MimeMessage(session)
                 message.setFrom(InternetAddress(fromEmail)) 
                 message.setRecipient(Message.RecipientType.TO, InternetAddress(toEmail))   
                 message.subject = "Test subject" 
                 message.setText("This is test email") 

                 Transport.send(message)
           }

      }
}

 // in MainActivity
 binding.btnAuthenticate.setOnClickListener {
        val toEmail = binding.etvInputUnivEmail.text.toString()
        GmailSender().sendEmail(toEmail)
 }