[cobalt-users] Raq4 to Raq4 Migration - MX and Mail question

["Paul Warner" <pwarner@xxxxxxxxxxxxxxxxxx>]

I am in the process of moving several sites from one 4i to another and want
this
to be as transparent to the users (and painless on all of us) as possible.

At present machine 'A' has sites, primary DNS, and mail for the domains in
question.
Machine 'B' is secondary DNS and low priority MX for these domains.

Will I eliminate incoming mail loss by flipping 'A' to low MX and 'B' to
high so that as DNS
changes propagate to the world, eventually any mail delivered using 'old'
DNS
entries indicating 'A' as preferred will be tossed to 'B' when 'A' looks at
the
new entries?  Is there a better way?

Can mail that is delivered to 'A' and passes on to the local user's account
be
automatically forwarded to 'B' where their new accounts reside, or do I need
to have
all users check pop by IP (so DNS won't be needed) on both servers, then
stop using
'A' IP and change 'B' IP to mail.domain.com?

I have other sites that are not moving, so I cannot completely shut off mail
on 'A' as was
suggested in the Archives...

Thanks!

Paul