We just switched from Open source to Network Edition last night with Archiving.
I've enabled and configured archiving for a few user accounts. I've already verified that new emails are showing up in the archive accounts.
Most of the users are currently setup with Outlook accessing their email via POP3, but we also have a few who only use the web client.
Here's what I'm currently thinking:
1. Enable archiving
2. Import PST
3. Backup user account
4. Restore emails from the backup to archive account
4. Cleanup user's account of old email
5. Switch user over to Zimbra Outlook Connector
How does that look and will it work?
Also, what would happen if there was a duplicate message being restored?