I am in the process of finishing a migration of our GroupWise system
from NetWare to Linux. I have everything there except for the GWIA. We
have several internal applications that are using our GWIA as a relay
for SMTP messages and because not all of the those apps use DNS names, I
would really like to create a new GWIA under a different domain. Then
we'll change the apps that use IP first then the DNS name. (The IP
address will not remain the same.)

I have M+Guardian on the perimeter and my MX record goes there. Once I
have the new GWIA setup, incoming mail should still go to the old GWIA
until I change the configuration of M+, correct?

What happens to people from inside sending out? Will they still go thru
the old GWIA by default or do I need to configure the new GWIA to
forward everything to M+ right away?

With this setup, I should be able to have the internal applications
reconfigured to send to the new GWIA and then monitor the log files and
then shut down the old GWIA when there is no traffic going thru it, correct?

I also have our current GWIA hosting our IMAP connections, but I know I
can change the DNS settings to redirect everyone to the new GWIA for that.

I have never run a system with two GWIA's and am unsure how the system
will act. Am I correct in all of the above? Any other gotchas I need
to think about?