the company i work there use a atmail appliane and latest version of atmail webmail+server software. it has some problems and we want to migrate to zimbra open source edition. there are some problem to migrate : 1- 1000 mailbox are usese now 2- 100 Gig is the space of users DATA. how can migrate to zimbra ??? the mailbox and data are very important and which distro ( linux like ubuntu or centos ) are recomnded for us .

thanks for helping me.