Hi everyone,

thanks for the attention and sorry if I created a new thread, if there is a solution already posted, pls give me the link.

I'm a newbie on zimbra and I should planning a migration from a pop3 server with Proxy to a Zimbra Open source Edition.

I should planning the installation for 2000 users... and i'm a bit scared, of how to balance it, the solution.
Because there isn't write how many users, the installation's of a medium or a large install is.
I'd like to install it on Vmware ESX, Ubuntu 10.04 (64bit)
1 ) How many Virtual machine should i create?
Tell me if i'm right please; i planned this :

1 - Proxy Imap VM,
1 - Ldap Server VM ( even if i'll use Active Directory to authenticate the users?) or it isn't necessary in the case of AD auth?
2 - Store, i thought 1000 user each...is it too much? How many users can manage each store?
1 - MTA server VM for sending. Is it too poor for 2000 user? How many mails, it can manage each MTA?

Another question is the size of Virtual Machine.

2 ) How big should be the Hard disk size of the Virtual machine?
for Proxy, and MTA 10gb with S.O is enought? i have no idea how much it can grow.

For the Store and Ldap?any advice?

3 ) If everything goes well and in the future i would migrate it, to Network edition is it possible to do it? I saw couple of links that i can do it in 2 ways... is there anybody that did it with the first solution? an easy backup and just install.sh of the NE....?!Is it so "easy"?
Should i backup just the Store and Ldap VM or every server?

i would keep, at the beginning, the old mail server to get a test of zimbra for some users, how can i use zimbra?

I thought this plan:

keep the old proxy, create a VM with ldap, mta, store, all in one, then set in the zimbra's admin, as relay server, the old mail server. Is it right?

How can i tell to the old mail server to check the user in zimbra server?
I mean, if i create users in zimbra and lock, the same users in the old mail server, to start getting email in zimbra, should i change something in the old proxy? or it's better if i create a VM with the Zimbra proxy, then use it instead of the old Proxy? In this case, how can i tell to Zimbra, how to send email to the accounts in the old mail server?

Thank you for the help.