$mail = new PHPMailer(true);
try
{
    //Tell PHPMailer to use SMTP
    $mail->isSMTP();
    $mail->SMTPDebug = 2;
    $mail->Debugoutput = 'html';
    $mail->Host = "smtp.gmail.com";
    $mail->Port = 587;
    $mail->SMTPAuth = true;
    $mail->SMTPSecure = "tls";
    $mail->Username = "username@gmail.com";
    $mail->Password = "pass";
    $mail->setFrom('username@gmail.com', 'First Last');
    $mail->addAddress("$mailto", 'John Doe');
    $mail->Subject = 'PHPMailer SMTP test';
    $mail->msgHTML("asdf");
    $mail->AltBody = 'This is a plain-text message body';
    $mail->AddStringAttachment($qr_base64, "Filename.png");
    $mail->send();
} catch (phpmailerException $e) {
    echo $e->errorMessage();
} catch (Exception $e) {
    echo $e->getMessage();
}