forwarding emails using sieve

[Thorsten von Eicken]

I know this is a tad tangential to dovecot, but maybe someone has some 
pointers for me. I'm trying to forward emails using the sieve filtering 
and redirect doesn't do it because it doesn't wrap the message in a new 
email, instead, it seems to just change the envelope From (and To). This 
causes the outbound relay to reject the message for security/spam 
reasons (forged From). It looks like the dovecot sieve implementation 
doesn't let me change the From header in the sieve script. Is there a 
way to accomplish what I'm looking for?

Thanks!