Added Nigel's og_mailinglist_postfix_transport.php file. Couldn't merge

as was committed with a number of other files that aren't ready to be
merged yet into the master branch.

postfix_og_mailinglist/og_mailinglist_postfix_transport.php

@@ -0,0 +1,55 @@
+#!/usr/bin/php
+<?php
+
+// Reads in raw email off the STDIN and posts the email using our curl command for the appropriate site.
+
+$raw_email = '';
+// Grab the raw email message from stdin.
+$fd = fopen("php://stdin", "r");
+while (!feof($fd)) {
+  $raw_email .= fread($fd, 1024);
+}
+
+// Set command line arguments (sent by the postfix transport) to variables.
+$parts = explode("@", $argv[1]);
+$mail_username = $parts[0];
+$mail_domain = $parts[1];
+
+// Load site info
+require_once('site_info.php');
+$sites = og_mailinglist_site_info();
+
+$post_url = "";
+$validation_string = "";
+// look for mail domain in site_info.php
+foreach ($sites as $domain => $info) {
+  if (strtolower($mail_domain) === $domain) {
+    $post_url = $info['post_url'];
+    $validation_string = $info['validation_string'];
+  }
+}
+
+if (empty($post_url)) {
+  echo "Could not match the email domain $mail_domain with a Drupal site. Check that you've setup site_info.php correctly.";
+  exit();
+}
+
+$token = md5($validation_string . $raw_email);
+
+$ch = curl_init();
+curl_setopt($ch, CURLOPT_RETURNTRANSFER, FALSE);
+curl_setopt($ch, CURLOPT_POST, 1);
+curl_setopt($ch, CURLOPT_HEADER, 1);
+curl_setopt($ch, CURLOPT_URL, $post_url);
+
+//prepare the field values being posted to the service
+$data = array(
+  'message' => $raw_email,
+  'token' => $token,
+  'group_name' => $mail_username,
+);
+
+curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
+
+//make the request
+curl_exec($ch);