WorldMail Server Move Situation

Hello All,

I have been now taske with moving my Eudora Worldmail 2.0 Server from a Public Address to a private address inside my network. I have very limited exposure to Email servers....so this is new to me.

I need to move my Eudora mail server from the public address, ionto my private address but am not sure what is the best...and quickest way to do so. And a few questions arise when I start thinking about the move.

What order should I move everything in?? I need to perform tasks to make this a smooth transition, but what would be the best way to attack it?

I have about 20 users on my network. Server Name will be different then the original server name.

I have to :
1. Install worldmail on the new machine.
2. Import all the user settings and mail stores.
3. Change DNS with MCI to point to the new mail server....(if the mailserver is on private IP how is that going to work?)


Here is the current layout of my net:

Mail server-----------\
                               \------------Watchguard Firebox700 Firewall ----Private Network
Web Server-----------/


So what I am thinking i need to do is install Worldmail, backup and migrate users from the old machine to the new...call MCI to change DNS......plan sounds ok...but not sure...and im not sure what IP i should give MCI for our new mail server.......the firewall ip? Probably really easy to do this, im just not up to par in the email department when it comes to things like this.

Any things I should be aware of? will i have to open ports on the firewall? how long for DNS change to take effect? ahhh so many questions, ....

thanks for any help!!!