I did upgrade to v.40 and had issues with DNS. I then installed a new mailinabox from scratch on new IP address and created everything again manually. (Users, Aliases, and Custom DNS)
Everything is now working.
But I have all my email history in the previous server.
What is the best way to get my old emails in the new server for each mailbox?
I found /home/user-data/mail/mailboxes/(domain)/(mailbox) but not sure if I need to copy all files or just copy cur, new, tmp files in the same directory in NEW server.
Any guidance would be appreciated!