Best way to merge to servers with overlapping user numbers?

freeloadermatt

I have two small grommunio instances which I would like to merge onto a single (fresh build) server: two users from one server and three from the other, onto a single instance with five users. The users are all in the same domain, i.e. aa@xx.com, bb@xx.com and so on.
Initial plan was to get database dumps and use rsync to bring the user directories over, but then I noticed that the user directories have overlapping id numbers like this:

server1:/var/lib/gromox/user/0/1
server1:/var/lib/gromox/user/1/0
server1:/var/lib/gromox/user/1/1
server2:/var/lib/gromox/user/1/0
server2:/var/lib/gromox/user/1/1

Question: What is the easiest way to merge these two sets of users onto a single server, while preserving all of their mailbox, contacts, calendars and other settings?
(any suggestions other than outlook PST export/import because that doesn't preserve inbox rules and some other settings)

crpb

New default format is /var/lib/gromox/user/domain.tld/user
mysql database grommunio.users has those mappings so you could move the folders accordingly to the new style and update the users.maildir in the database.
Or setup a new system and rsync from both servers after just creating the users to have them already and all you need is something like

select substring_index(username, "@", 1) as user, substring_index(username, "@", -1) as domain from users ;

EDIT..

SELECT
  substring_index(username, "@", 1) AS USER,
  substring_index(username, "@", -1) AS DOMAIN,
  maildir AS oldmaildir,
  concat('/var/lib/gromox/user/', substring_index(username, "@", -1), "/", substring_index(username, "@", 1)) AS newmaildir
FROM users ;

Well, that could also be extended to retrieve the domain via users.domain_id but that should already be enough in most cases i think