Use of email Redirection.
By creating an email redirection, messages are sent to a different email address without requiring the sender to know the new email address. Email can be redirected to any email address (outside the current domain also).
In order to set a redirection for the email address in plesk control Panel, follow the following steps:
1. Log in to Plesk control panel.
2. Click on "Domains".
3. Click on the domain name under whome you want to make the changes.
4. On the mail name properties page, click the Redirect icon.
5. Select the Redirect checkbox, and in the text box to the right, enter the appropriate
email address on which all the emails should be forwarded.
6. Click OK.
You may click here for flash tutorial for creating "Email Forwarder" in Plesk.