1) Wait until Ubuntu 10.04 is supported - it is slated for 6.0.8, but its better to be safe than sorry.
Since you're on NE, I'd suggest setting up a new mailbox server on the 64-bit platform with the new hostname, add it to your existing setup as a second server, and then preform the mailbox move procedure to move all of the users mailboxes over to it. You can then move accounts in a staged fashion to allow you time to make sure each user goes uninterrupted. Also add LDAP/MTA services to the new server, and then promote the new server's LDAP to be the master. Once you have everything migrated off, you could then remove the older 32-bit server from the setup. |