How do I change the global site url when serving Drupal from behind a reverse proxy? I want the site name to be the FQDN instead of the machine's internal name (ie: localhost), especially in tokens.
I'd like to be able to change the value once (like say in an env var) so it shows up any time the site's url needs to be used, say in automated emails.

aggravating factor: we're using IIS7
inside settings.php:

global $base_url;
$base_url = 'http://my.domain.name';