migrate Maildir to mdbox

Hi,

I replaced HDDs in my home server and reinstalled the OS (Ubuntu 17.04). Since I had some time I reviewed my Dovecot configuration and changed a couple of things, including mailbox format.

Now I would like to migrate e-mail (about 20G -- I use this server as an e-mail archive). The Maildir is available on the (old) hard disk. The new dovecot is running. What should I use? Would mbsync work? I would prefer a solution that does not mess up the UUIDs, but I can live with that too.

$ dovecot --version 2.2.27 (c0f36b0)

Incidentally, would you recommend sdbox or mdbox? Lots of e-mails, many of them have large attachments.

best,

Tamas