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

Sending email programmatically with Kotlin.

• simple email sending, not all the other features (like attachments).
• TLS is always on
• Only 1 gradle email dependency needed also.

I also found this list of email POP services really helpful:

https://support.office.com/en-gb/article/pop-and-imap-email-settings-for-outlook-8361e398-8af4-4e97-b147-6c6c4ac95353

How to use:

    val auth = EmailService.UserPassAuthenticator("you@gmail.com", "yourPassword")    val to = listOf(InternetAddress("to@email.com"))    val from = InternetAddress("you@gmail.com")    val email = EmailService.Email(auth, to, from, "Test Subject", "Hello Body World")    val emailService = EmailService("smtp.gmail.com", 465)    GlobalScope.launch { // or however you do background threads        emailService.send(email)    }

The code:

import java.util.*import javax.mail.*import javax.mail.internet.InternetAddressimport javax.mail.internet.MimeBodyPartimport javax.mail.internet.MimeMessageimport javax.mail.internet.MimeMultipartclass EmailService(private val server: String, private val port: Int) {    data class Email(        val auth: Authenticator,        val toList: List<InternetAddress>,        val from: Address,        val subject: String,        val body: String    )    class UserPassAuthenticator(private val username: String, private val password: String) : Authenticator() {        override fun getPasswordAuthentication(): PasswordAuthentication {            return PasswordAuthentication(username, password)        }    }    fun send(email: Email) {        val props = Properties()        props["mail.smtp.auth"] = "true"        props["mail.user"] = email.from        props["mail.smtp.host"] = server        props["mail.smtp.port"] = port        props["mail.smtp.starttls.enable"] = "true"        props["mail.smtp.ssl.trust"] = server        props["mail.mime.charset"] = "UTF-8"        val msg: Message = MimeMessage(Session.getDefaultInstance(props, email.auth))        msg.setFrom(email.from)        msg.sentDate = Calendar.getInstance().time        msg.setRecipients(Message.RecipientType.TO, email.toList.toTypedArray())//      msg.setRecipients(Message.RecipientType.CC, email.ccList.toTypedArray())//      msg.setRecipients(Message.RecipientType.BCC, email.bccList.toTypedArray())        msg.replyTo = arrayOf(email.from)        msg.addHeader("X-Mailer", CLIENT_NAME)        msg.addHeader("Precedence", "bulk")        msg.subject = email.subject        msg.setContent(MimeMultipart().apply {            addBodyPart(MimeBodyPart().apply {                setText(email.body, "iso-8859-1")                //setContent(email.htmlBody, "text/html; charset=UTF-8")            })        })        Transport.send(msg)    }    companion object {        const val CLIENT_NAME = "Android StackOverflow programmatic email"    }}

Gradle:

dependencies {    implementation 'com.sun.mail:android-mail:1.6.4'    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.3"}

AndroidManifest:

<uses-permission android:name="android.permission.INTERNET" />