No success yet.
Before (10-mail.conf)
unix_listener auth-userdb { #mode = 0666 #user = #group = }
After
# grep ^auth_socket_path 10-mail.conf auth_socket_path = /var/run/dovecot/auth-userdb
# grep -A 5 'unix_listener auth-userdb' 10-master.conf unix_listener auth-userdb { #mode = 0666 user = mail group = mail }
shared-mailboxes.db is present
# ll /var/mail/mymail.domain/shared-mailboxes.db -rw-rw---- 1 mail mail 120 apr 4 17:12 /var/mail/mymail.domain/shared-mailboxes.db
If I delete the file /var/mail/mymail.domain/shared-mailboxes.db, it will still be created
# cat /var/mail/mymail.domain/shared-mailboxes.db shared/shared-boxes/user/domainuser1/apr07@mymail.domain 1 shared/shared-boxes/user/domainuser1/domainuser2@mymail.domain 1
(domainuser2 share "newfolder1" for domainuser1. And apr07 share "sharefolder" for domainuser1)
# ll /var/mail/mymail.domain/apr07/dovecot-acl-list -rw------- 1 mail mail 23 apr 7 17:11 /var/mail/mymail.domain/apr07/dovecot-acl-list
# cat /var/mail/mymail.domain/apr07/dovecot-acl-list 1744027894 sharefolder
# cat /var/mail/mymail.domain/domainuser2/dovecot-acl-list 1744027957 newfolder1
# ll /var/mail/mymail.domain/domainuser2/ | grep newfolder1 drwx--S--- 5 mail mail 4096 apr 7 17:12 .newfolder1/
# ll /var/mail/mymail.domain/apr07/ | grep sharefolder drwx--S--- 5 mail mail 4096 apr 7 17:11 .sharefolder/