Split domain migration with multiple domains on old server

[atlee]

Our current CommuniGate Pro server hosts 500 accounts for our main domain, and 2000 accounts in 35 domains also hosted on the CGP box.

The 500 main domain accounts will be migrated to a new Zimbra box, while the other domains and their accounts will remain on the old CGP host. We will employ the split domain solution explained in the wiki.

The wiki explains that all accounts on the old host need corresponding accounts on the new, primary host that will be doing routing. Will we need to set up these "pointer" accounts within domains on the Zimbra box that correspond to the domains on the old, now secondary, CGP host?

[atlee]

Since we are splitting only our main domain's accounts, and not the hosted domains' accounts. Can we leave the hosted domains' MX records and accounts alone, and have parallel accounts and Zimbra smart host routing for the main domain accounts only?