If you were provided with internet access to e-mail using a web browser, there is likely a link to a setup page that may allow you to control forwarding of your e-mail.
By forwarding at the e-mail server level, forwarding will occur even if your Outlook e-mail program is not running.
If you can't find the link to setup forwarding, call your ISP's help desk. They will be able to tell you if forwarding is available and how to access the setup page.
Most e-mail servers allow forwarding, as well as automatic response messages.