Intent.EXTRA_EMAIL not populating the To field

Use this

public void Email(){
    // use this to declare your 'recipient' string and get your email recipient from your string xml file
    Resources res = getResources();
    String recipient = getString(R.string.IntegralEmailAddress);
    Intent emailIntent = new Intent(Intent.ACTION_SEND); 
    emailIntent.setType("message/rfc822");  //set the email recipient
    emailIntent.putExtra(Intent.EXTRA_EMAIL, recipient);
    //let the user choose what email client to use
    startActivity(Intent.createChooser(emailIntent, "Send mail using...")); 

``}

This will work :)
This is what android documentation says about Intent.Extra_Email
-A string array of all "To" recipient email addresses.
So you should feed string properly You can read more over here
http://developer.android.com/guide/components/intents-common.html#Email and here http://developer.android.com/guide/topics/resources/string-resource.html Or use the ACTION_SENDTO action and include the "mailto:" data scheme. For example:

Intent intent = new Intent(Intent.ACTION_SENDTO);
intent.setData(Uri.parse("mailto:")); // only email apps should handle this
intent.putExtra(Intent.EXTRA_EMAIL, addresses);
intent.putExtra(Intent.EXTRA_SUBJECT, subject);
if (intent.resolveActivity(getPackageManager()) != null) {
    startActivity(intent);
}

Couple of things:

1 - You need to set the action constant variable as ACTION_SENDTO.
Intent intentEmail = new Intent(Intent.ACTION_SENDTO);

2 - If you want it to be opened by only the mail then use the setData() method: intentEmail.setData(Uri.parse("mailto:")); Otherwise it will ask you to open it as text, image, audio file by other apps present on your device.

3 - You need to pass the email ID string as an array object and not just as a string. String is: "[email protected]". Array Object of the string is: new String[] {"email1", "email2", "more_email"}.

intentEmail.putExtra(Intent.EXTRA_EMAIL, new String[] {"[email protected]", "[email protected]"});

In Kotlin - Android

fun sendMail(
        activity: Activity,
        emailIds: Array<String>,
        subject: String,
        textMessage: String
    ) {


        val emailIntent = Intent(Intent.ACTION_SEND)
        emailIntent.type = "text/plain"
        emailIntent.putExtra(Intent.EXTRA_EMAIL, emailIds)
        emailIntent.putExtra(Intent.EXTRA_SUBJECT, subject)
        emailIntent.putExtra(Intent.EXTRA_TEXT, textMessage)
        emailIntent.setType("message/rfc822")
        try {
            activity.startActivity(
                Intent.createChooser(
                    emailIntent,
                    "Send email using..."
                )
            )
        } catch (ex: ActivityNotFoundException) {
            Toast.makeText(
                activity,
                "No email clients installed.",
                Toast.LENGTH_SHORT
            ).show()
        }
    }

Also you can use [ val emailIntent = Intent(Intent.ACTION_SENDTO) ] to invoke direct email client

//argument of function
val subject = "subject of you email"
val eMailMessageTxt = "Add Message here"

val eMailId1 = "[email protected]"
val eMailId2 = "[email protected]"
val eMailIds: Array<String> = arrayOf(eMailId1,eMailId2)

//Calling function
sendMail(this, eMailIds, subject, eMailMessageTxt)

I hope this code snippet will help to kotlin developers.

I think you are not passing recipient as array of string

it should be like

emailIntent.putExtra(android.content.Intent.EXTRA_EMAIL,new String[] { "[email protected]" });