Hook to catch a variable in a POST request to a specific url? I'm testing an external email collection service that appears periodically at certain time intervals on a site.

When a user completes the form, the application can pass the email address as a variable in a POST request to a specific url.

What hook should I use to catch and process the email address at this one specific url?

I thought of using hook_init() something like the following, but I'm not sure if this is a good way to do something like this?

/**
 * Implements hook_init()
 * Check for variable sent via POST and process if found
 */
function mymodule_init() {
  if (drupal_get_path_alias() == "myurl") {
    if (isset($_POST['email_variable'])) {
      &lt;custom processing&gt;;
    }
  }
}


Notes:


The url is a normal node page that already exists on the site.
The form is externally hosted, so a form alter is not an option.
You should use the services module to create an endpoint and use the url where is sent as the path to endpoint.

You don't state which type format the data is being posted to your site but the services module can handle many different types.

Also it's not stated exactly what you want to do with the received data but the services module can be set up to process it in a variety of ways.

You can capture it to a databse table etc 
or Here's an example of creating a node using services:
http://www.drupalwoo.com/content/blog/drupal-services-creating-node-from-external-form