i had a debian 9+virtualmin with email (postfix/dovecot) and move to debian 10 at a new server (new ip+machine)…
my web pages fix and works… but my email… after worked only for incoming i ve made a stupid think - copied from old server (all homes directory to my new server and replace them all) - i wanted to have the new mails came at middle of transfer…
now at client side i am taking the message of “STAT failed” error… internal error occured… something goind up with the indexes…
You will have to comply with best practices for migrating a website from one server to another. It is extremely easy to do this from a Virtualmin system to a Virtualmin system but you cannot go around copying over files randomly and get everything to work.
My Hosting company says that i must setup hostname the time of installation (debian)… because i can;t change it (every time reboot come at the default)… so it is a good time to reinstall as i have a previous backup… and i ll sync with imap… or something…