Step by step guide on how to configure Email Forwarding in the Office 365 Admin Portal
In the admin center, go to the Users > Active Users Page.
Select the name of the user whose email you want to forward to open the properties page.
On the Mail tab, select Manage email forwarding.
On the email forwarding page, select Forward all emails sent to this mailbox, enter the forwarding address, and choose whether you want to keep a copy of forwarded emails. If you don't see this option, make sure a license is assigned to the user account. Select Save changes.