A working script to schedule a newsletter.

nlapisch.php

<?php
$url = 'http://sendgrid.com/';
$user = "sebfree";
$pass = "******";
$nl_name = "NLAPI_test3";
$send_time = "2013-07-25T09:00:00+02:00";
  
  $params = array(
          'api_user' => $user,
          'api_key'  => $pass,
          'name'     => $nl_name,
          'at'     => $send_time
           );
 
$request = $url.'api/newsletter/schedule/add.json?';
$session = curl_init($request);
 
curl_setopt ($session, CURLOPT_POST, true);
curl_setopt ($session, CURLOPT_POSTFIELDS, $params);
curl_setopt($session, CURLOPT_HEADER, false);
curl_setopt($session, CURLOPT_RETURNTRANSFER, true);
 
$response = curl_exec($session);
curl_close($session);
 
print_r($response);
?>