I need to move, make exact copy from one dovecot server v.2.0.19 on Ubuntu 12.04.5 LTS to another server, dovecot 2.2.22 running on Ubuntu 16.04.1 LTS. The task is everything to be as smooth as possible and the users of the email accounts to not lose any information. All IMAP folders structure should be preserved intact. The users should use only the new server in the future.
I found dsync as suitable command, however it seems that I can not use it to migrate from dovecot 2.0 to 2.1 or 2.2. dsync requires v.2.1.4+. So I decided to first upgrade the source server to whatever v. 2.1.4+. However I don't know how to do this. It is server with lot's of things on it like spamassasin, ISPconfig etc.
So how should I upgrade the server? I found an answer here in another thread however when I tried it I got an error messages and everything went wrong.
Please provide me with step by step how to. Thanks a lot.