How do I change the TO: field in a redirect?

[Graham@]

I want to set up a redirect as follows:

address1@domain1.com

to

address2@domain2.com

BUT - the TO: address needs to change from 1 to 2.

As far as I can tell, Plesk's redirect keeps the TO: address the same, simply adding an ENVELOPE-TO: address for address2

It's essential I change the TO: address.

How can I do that?

Graham