doveadm -o mail_gid=testgroup2 mailbox create -u usertest public/publictest1

public/mdbox/mailboxes) failed: Operation not permitted

[@public]# getfacl mdbox/ # file: mdbox/ # owner: root # group: root user::rwx group::rwx group:testgroup2:rwx group:testgroup3:rwx mask::rwx other::---