gistfile1.php

<?php

$apikey = 'API_KEY_HERE';

require_once 'Mandrill.php';
$mandrill = new Mandrill($apikey);

$message = new stdClass();
$message->html = "html message";
//$message->text = "text body";
$message->subject = "email subject";
$message->from_email = "from@email.com";
$message->from_name  = "My App Name";
$message->to = array(array("email" => "recipient@email.com"));
$message->track_opens = true;

$response = $mandrill->messages->send($message);

var_dump($response);
?>