Unusual Email Forward Setup Help request

Hi,

I have an email account eg. george@olddomain.com and want to forward all emails from a specific client eg. abc@thisdomain.com, def@thisdomain.com (etc) to another email account at a different domain eg. george@newdomain.com.

The forward setting in cPanel allows me to do this but is really just redirecting the email so when I receive the forwarded email it says its from abc@thisdomain.com or who ever sent the original email - I need the forwarded email to be properly forwarded from the george@olddomain.com so that all emails I get at the george@newdomain.com account come from the same george@olddomain.com email address regardless of the original sender.

Any ideas how I could do this with either within the filter or forward settings or utilising a pearl script?

Cheers,

Geo.