I'm evaluating options for migrating our ZCS Network Edition 6.0.15 installation to 8.x (either ZCS NE or ZCA (Appliance)). We've got about 2.500 domains and about 20.000 mailboxes.

I know about the ZeXtras toolkit, but it doesn't work for me (login to admin console hangs/doesn't work - I'm in contact with them). Because of that, I'm looking for other options. One would be to use zmztozmig; for this, I read the Zimbra to Zimbra Migration wiki page.

It says:

Quote Originally Posted by Zimbra to Zimbra Migration wiki page
When zmztozmig is used to import files, after the data is imported, the data in the accounts on the destination server are not an exact replica of the data in the accounts on the source server. And account preferences are not imported. Also, if the destination accounts do not have the same account IDs as they had on the source server, files that were shared and appointments related to the original sender might not work.
Account preferences, I might understand and accept, especially seeing that we're going from Zimbra 6 to 8.

But losing shared files and appointments wouldn't be so great. Can you provide some hints, about how I could make sure, that the account IDs match?

And is that truly all that will be lost? What about filter rules and signatures? Do they "survive" a migration — or is that part of the "account preferences"? Any workarounds, to not lose that?