Try forwarding a message to an email address you have with some other email provider like Gmail or Yahoo or something. Does it work OK?
No. Tried my gmail and it didn't go through. I can compose and send an email though.
Are you seeing anything unusual when you try to forward an email? I tried using both the arrow in the toolbar, and the link in the header and they both work fine. Although using one particular message when I hit the arrow I got a display saying there are 3 messages in a conversation, and I had to pick one to forward.