reroute mail based on headers

[Ryan Suarez]

Greetings,

I would like to reroute mail for all our recipients if a certain header 
is present.

Eg. Mail to 'm...@mydomain.org' has the header 'SomeHeader'.  I would like 
to reroute this email to 'm...@some-server.mydomain.org'. 

What is the best way to accomplish this in postfix?

thanks,
Ryan