Check out
this thread for zmlmtpinject syntax.
Your message store should be structured like this:
Code:
/opt/zimbra/store/{hash}/{mailbox-id}/msg/{hash}/{item}.msg In other words, all messages in an on-disk directory belong to the same user. So, once you've determined whose mailbox the messages correspond to, just use zmlmtpinject to inject them into the new Zimbra M2 server. You'll lose tags, contacts, folder structure, received dates, and read/unread status, but it should work.
If you want to be extra-tricky, before you run zmlmtpinject you can write a perl script to add an extra "X-Zimbra-Received" header to each message, with the value being the same as the "Date:" header's value. Then zmlmtpinject will use that date as the "received date" when re-injecting the messages.