stop accepting mail and clear mailq

[J.P. Trosclair]

Is there a way to put postfix in state so that it stops accepting mail 
so that I can clear the queue of all undelivered mail?

Rundown of what and why:
We are a small company, we have two mail servers (mail1, mail2). Mail1 
is our primary server, mail2 pretty much just sits there to be used for 
special tasks like the one I'm planning or as a replacement if mail1 
takes a total meltdown.

I'm planning to bring mail1 down this weekend to create backup images of 
the entire disk. Before I create the images I want to flush the mail 
queue and temporarily move the user's mailboxes to a storage location so 
they are not included in the imaging process. I also want to have the 
mail queue on mail1 clean before I bring it completely down.

My plan to do this is to reconfigure mail2 to accept mail for our domain 
and queue it to be forwarded to mail1 once it comes back online (I think 
this should be transparent with minimal impact for mail being 
undeliverable if I change the routing in our network for our MX host to 
go to mail2, comments or suggestions on this are appreciated). At some 
point mail1 will be online still accepting mail and mail2 will be online 
receiving and accepting mail for the same domain as well as attempting 
to forward it to mail1 and queuing it if mail1 doesn't answer. I want to 
force mail1 not to accept the mail and flush any remaining mail to the 
user's mailboxes for the reasons I mentioned in the paragraph above.

J.P.