To enable auto-forwarding of email within ESM:
- Drill down in ESM into Global Settings or hub transport (exchange 2007)
- Right-click on Internet Message Formats in the left pane.
- Then double-click the Default format in the right pane.
- Select the Advanced tab, and then verify that "Allow Automatic Forwards" is enabled.
Message Format tab for remote domain properties
here in this link how to create e-mail fowarding rules in outlook web access
more about Managing Remote Domains setting in this link