I've recently gone through a server migration of 20 or so domains, none
of which had a ton of email in them.
Here's what I did:
1. add domain to new server using vadddomain
2. stop qmail-send on old server
3. tar/gzip /home/vpopmail/domains/domaintomove.com directory
4. Move to new server and untar into place, overwriting
existing vpasswd and postmaster files.
5. vdeldomain on the old server
6. add domain to rcpthosts on old server
7. add domain:newserver to smtproutes on old server
8. restart qmail-send
9. change DNS.
This worked fine for my small server with few messages and few clients
that would notice anything strange.
However, I've been asked to do the same on another mail server with
several hundred domains and 15 gig of mail. In order to transfer one
domain with lots of mail, I could potentially have to have the stuff
down for an extended period of time. I don't want people reading email
while I'm tarring up their domain's email.
My question is... is there a better way than the steps I described above?