Step 1. Navigate to portal.office.com and Sign in with your email and password.
Step 2. Click the Square in the top left and then click on Mail
Step 3. Click the Cog in the top right to bring you to settings, click mail down the end to bring up Mail Options
Step 4. Click on forwarding under the Mail options click start forwarding enter the email address you want to forward to and hit Save.
Note: this is permanent until turned off again.