科特林：

val email: String = getEmail()
val intent = Intent(Intent.ACTION_SENDTO)
intent.data = Uri.parse("mailto:$email" )
startActivity(intent)

如果您想要以Gmail为目标，那么您可以执行以下操作。注意，意图是“ACTION_SENDTO”而不是“ACTION_SEND”，额外的意图字段对于Gmail是不必要的。

String uriText =
    "mailto:youremail@gmail.com" + 
    "?subject=" + Uri.encode("your subject line here") + 
    "&body=" + Uri.encode("message body here");

Uri uri = Uri.parse(uriText);

Intent sendIntent = new Intent(Intent.ACTION_SENDTO);
sendIntent.setData(uri);
if (sendIntent.resolveActivity(getPackageManager()) != null) {
   startActivity(Intent.createChooser(sendIntent, "Send message")); 
}

根据Android开发者官方文档，这是发送电子邮件意图的正确方式

添加以下代码行到你的应用程序:

Intent intent = new Intent(Intent.ACTION_SEND);//common intent 
intent.setData(Uri.parse("mailto:")); // only email apps should handle this

可选:添加主体和主题，就像这样

intent.putExtra(Intent.EXTRA_SUBJECT, "Your Subject Here");
intent.putExtra(Intent.EXTRA_TEXT, "E-mail body" );

你的问题里已经加了这句话

intent.putExtra(Intent.EXTRA_EMAIL, new String[]{"hello@example.com"});

这将是收件人的地址，这意味着用户将向您(开发人员)发送电子邮件。

适用于所有android版本:

String[] to = {"email@server.com"};
Uri uri = Uri.parse("mailto:email@server.com")
  .buildUpon()
  .appendQueryParameter("subject", "subject")
  .appendQueryParameter("body", "body")
  .build();
Intent emailIntent = new Intent(ACTION_SENDTO, uri);
emailIntent.putExtra(EXTRA_EMAIL, TO);
startActivity(Intent.createChooser(emailIntent, "Send mail..."));

更新到Android 10，现在使用Kotlin…

fun Context.sendEmail(
  address: String?,
  subject: String?,
  body: String?,
) {
  val recipients = arrayOf(address)
  val uri = address.toUri()
    .buildUpon()
    .appendQueryParameter("subject", subject)
    .appendQueryParameter("body", body)
    .build()
  val emailIntent = Intent(ACTION_SENDTO, uri).apply {
    setData("mailto:$address".toUri());
    putExtra(EXTRA_SUBJECT, subject);
    putExtra(EXTRA_TEXT, body);
    putExtra(EXTRA_EMAIL, recipients)
  }
  val pickerTitle = getString(R.string.some_title)
  ContextCompat.startActivity(this, Intent.createChooser(emailIntent, pickerTitle, null)
}

.．.在更新到API 30之后，代码没有填充电子邮件客户端的主题和主体(例如Gmail)。但我在这里找到了答案:

fun Context.sendEmail(
  address: String?,
  subject: String?,
  body: String?,
) {
  val selectorIntent = Intent(ACTION_SENDTO)
    .setData("mailto:$address".toUri())
  val emailIntent = Intent(ACTION_SEND).apply {
    putExtra(EXTRA_EMAIL, arrayOf(address))
    putExtra(EXTRA_SUBJECT, subject)
    putExtra(EXTRA_TEXT, body)
    selector = selectorIntent
  }
  startActivity(Intent.createChooser(emailIntent, getString(R.string.send_email))) 

}

试一试:

intent.setType("message/rfc822");

使用intent.setType(”消息/根据rfc822”以);工作，但它显示额外的应用程序，不一定处理电子邮件(如GDrive)。使用意图。ACTION_SENDTO与setType("text/plain")是最好的，但你必须添加setData(Uri.parse("mailto:"))，以获得最好的结果(仅电子邮件应用程序)。完整代码如下:

Intent intent = new Intent(Intent.ACTION_SENDTO);
intent.setType("text/plain");
intent.setData(Uri.parse("mailto:IT@RMAsoft.NET"));
intent.putExtra(Intent.EXTRA_SUBJECT, "Email from My app");
intent.putExtra(Intent.EXTRA_TEXT, "Place your email message here ...");
startActivity(Intent.createChooser(intent, "Send Email"));