mail server host names during migration

Hello,

I am wanting to do a migration for my mail server that is running Zimbra open source (32bit). I have a new server that I am migrating to and I am curious if the hostname should be the same as the one I am migrating from. Also should the new mail server have the same IP as the old. I understand that they could not be on the network at the same time.

Thanks

Don Hickey