You need to forward from the mail server -- not from your PC. Your PC can't forward email while it's off.
Originally Posted by cityadmin
Being able to use the webmail interface would be very helpful because some messages are automatically sent to folders other than "inbox" on the desktop machine. I don't get those at all.
How exactly is mail moved into the subfolders? If it's a rule running on your PC then forwarding from the mail server should solve that as well.