quick query re forwarding local mail to another server

[Carl Brewer]

I'm having to do an urgent job on a postfix box that I'm not overly 
familiar with, and it involves moving to a new server.

I've got a bunch of local accounts and while the move is happening I 
need the local accounts emails to be forwarded to the new box, which has 
the same accounts on it.

The 'old' box has a number of processes on it that send email, and I 
need to get postfix on that box to not send the mail to the local (to 
the old box) mail spool files, but to deliver them to the new server.  I 
have a pile (some 100 or so) of local mail boxes on the old server 
listed in virtual and their domains in relay_domains.cf that all need to 
be pushed to the new box.

I've set up the relayhost in main.cf to point to the new server, but 
AFAIK that just does outgoing mail. I've changed the MX records for all 
the domains that point at the old server so that incoming mail will soon 
trickle to a halt, but that doesn't solve the whole problem, if postfix 
sees mail for an address it thinks it hosts, it wants to deliver it 
locally.  Should I just kill off all the entries in relay_domains.cf and 
virtual to stop it doing that so it sends everything to the relayhost?

I don't think luser-relay is the right way to do this, can anyone point 
me at the quick & dirty way to do this, or the appropriate section of 
the postfix documentation?

Thankyou!

Carl