PHP SMTP mail function doesn't send mail with concatenated string address
<?php
require_once "Mail.php";

$host = "smtp.domain.com";
$username = "user@domain.com";
$password = "validpass";

if(isset($_POST['submit'])) {
    $address = $username.$mailprovider;
    $emailTo = $address;
    $body = "Name: $name nnMessage: $message";

    $headers = array ('From' => 'user@domain.com',   'To' => $emailTo,   'Subject' => 'test');

    $smtp = Mail::factory('smtp', array('host'=>$host, 'auth'=>true, 'username'=>$username, 'password'=>$password));

    $mail = $smtp->send($emailTo, $headers, $body);


    if(PEAR::isError ($mail)){
        echo("<p>. $mail->getMessage().</p>");
        } else {
        echo("<p>Message successfully sent!</p>");
        }

    $emailSent = true;

}

?>