Redundant mail server

[Curtis Vaughan <curtis@npc-usa.com>]

Not sure whether redundant is the right word. Anyhow here's the 
question:

We have an office in the US and overseas.
The mailserver used by the overseas office is in the US office. Of 
course, occassionally there may be downtime for the US office. So the 
overseas office has this idea that we could set up a backup mail server 
in their office. They would then use the backup mail server should the 
server in the US office be down.

Well, I've explained to them that that won't really work - which the IT 
admin over there agrees with, but then keeps pursuing the question. So, 
I want to know definitively whether I am right or not.

The problem as I see it is this. Fine they have a redundant server, but 
it wouldn't be able to recieve any mail, because the domain name for 
the  mail server points to the US office. There is no way that I'm 
aware of to rapidly switch the IP address of the mail's domain name and 
then switch it back when the US office mail server is back up.

Thanks for any input.