Cannot Redirect Mail to external address

[hedgefighter]

I'm trying to get a mail redirect to work on an Ubuntu server. I can receive mail fine, send mail fine, use an automatic reply fine, pretty much everything works. But I can't get mail forwarding to work. I can forward to an address in the same domain but it won't forward to my gmail address. I checked my maillog and it says the forwarded message was accepted, but I never receive it. Any help?