I used imapsync https://imapsync.lamiral.info/doc/TUTORIAL_Unix.html from outlook.office365.com to ISPConfig e-mail server. It looks like the e-mails are synched and I got 1.1 GB of files and directories to /var/vmail, but the folders are not visible. Nor are the e-mails in those folders. I can see in Roundcube and Thunderbird the default folders Drafts, Sent, Junk and Trash, but not the folders created by user of the old mailbox. Is this some setting in Dovecot? I discovered my e-mail server has setting Code: mail_location = mbox:~/mail:INBOX=/var/mail/%u in file /etc/dovecot/conf.d/10-mail.conf which is strange since dovecot is using Maildir, not mbox. So that setting seems to be overridden by ISPConfig Panel System | Server Config | Mail tab settings. The imapsync tutorial by Falko Timme looks a decade old, might still be OK. But it does not mention this folders not visible problem.
Probably the mail client has not subscribed to the folders yetm, see: https://www.supportpro.com/blog/subscribe-imap-folders-in-webmail-and-different-email-clients/
Config files in /etc/dovecot/conf.d/ are not used by dovecot, so it does not matter what's in there. The whole dovecot configuration is in dovecot.conf file.
Fine answer as usual on Howtoforge. Those folders become visible when subscribed. I have never known about subscribing folders, but learning something new every day.
