This is caused by an anonymous socket communication channel between dovecot and anvil. If this problem is not happening in 16.04 (unless you are using the release kernel) then it will be because o a change to dovecot, newer versions of apparmor have been SRUed back to 16.04
This is caused by an anonymous socket communication channel between dovecot and anvil. If this problem is not happening in 16.04 (unless you are using the release kernel) then it will be because o a change to dovecot, newer versions of apparmor have been SRUed back to 16.04