forwarding emails using sieve

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!