This is not really directly directly connected about Zimbra itself, but does have something to do with the provision of the service, so I thought I would drop the question in here.

Everything is working well on the LAN, but when external users view the Zimbra interface, the proxy service on our firewall stops the ajax functionality strips all of the functionality out, so users just have a grey screen!

These are all stopped by the HTTP Proxy service:

Path: /js/msgs/I18nMsg,AjxMsg,ZMsg,ZmMsg.js.zgz?v=060414125745
Path: /js/Ajax_all.js.zgz?v=060414125745
Path: /zimbra/js/ZimbraMail_all.js.zgz?v=060414125745

I can solve this by adding the content type into the firewall and allowing the .js.zgz content type through, but I don't know what the mime type for this is. Is it multipart or application?

Any help is appreciated