Log in to your Plesk account;
Go to Mailbox;
Click on your email address;
Then click on Forwarding;
Check the box Enable mail forwarding;
Specify one or more email addresses for mail forwarding;
By default, copies of forwarded mail remain in the Plesk mailbox. To have Plesk automatically delete copies, check the box Do not save copies of forwarded mails in Plesk mailbox;
Click on OK