store, data and db directories are all under /opt/zimbra
I recreated each domain and user on the new server. I set the account passwords on the old server and new server to something common.
I used imapsync as follows :-
You may have to change the --noauthmd5 and --tls2 flags depending on your server setup.
#make sure passwords are the same for both accounts
for i in account1 account2 accountN ; do
imapsync --host1 10.0.0.1 --user1 $ACCOUNT --password1 $PASS --host2 10.0.0.2 --user2 $ACCOUNT --password2 $PASS --noauthmd5 --tls2;