We'll need more infomation
What server are you running on the lan? I don't run suse but when I setup my gentoo system it was very easy to have it forwarding all my email to root/my user to my gmail account but I'm not sure how you'd copy the email to an external address so thats why we need to know what mail server
Do people pickup the email from their normal address (xxx@vf.co.zw) or do you JUST want it from the gmail address?
Cheers,