Log in to the Plesk administration tool. (Forgot password?)
Select the E-Mail menu and the desired email address.
You can now define whether you want to set up forwarding with an active mailbox, so that messages are stored on the server and can be accessed via webmail or email client (forwarding), or if the mailbox should be deactivated so that messages are only forwarded without being stored on the server (redirect). The article Difference Between Forwarding and Redirect explains the difference between forwarding and redirect in detail.
Forward and Save (Forwarding)
Click on the Forwarding tab and check the box for Enable email forwarding. Now enter the desired email address under "Forward incoming messages to the following email address."
Forward Without Saving (Redirect)
Uncheck the box for Email mailbox so that emails are not stored locally.
Click on the Forwarding tab and check the box for Enable email forwarding. Now enter the desired email address under "Forward incoming messages to the following email address."