AutoChimp behind a proxy

I have AutoChimp running fine on our development server. Site now going live onto client’s server in their DMZ. I have outgoing port 8080 to a proxy server and have set the following in /wp-config.php:

define(‘WP_PROXY_HOST’, ‘XXX.XXX.XXX.XXX’);
define(‘WP_PROXY_PORT’, ‘8080’);
define(‘WP_USEPROXY’, ‘TRUE’);

After I did this WordPress gained access to the outside World and things like the news feeds on the dashboard page and plugin update alerts started working. However, AutoChimp refuses to work. There is a long delay when clicking AutoChimp in the settings menu before anything displays and then, despite a valid API key, I get the following under Mailing List Management:

“Unable to retrieve your lists with this key! Did you paste it in correctly? Visit the API Key tab and try again, just in case. If you know it is correct, make sure you’re connected to the internet and not working offline”

Publishing or Updating posts takes a long time, sometimes times-out, with AutoChimp Active. Deactivate and it’s as snappy as usual.

Do I need to ask the client to open any pinholes in the firewall?

This is on a Windows 2008 R2 64bit server, yes I know… However, runs fine elsewhere, it just seems to be an environment issue.

Thanks.

http://wordpress.org/plugins/autochimp/