(http://www.iredmail.org/docs/public.folder.html)

-+namespace {
type = public
separator = /
prefix = Public/ +-

-+# CONTROL=: Mark this public folder as read-only mailbox

1. INDEX=: Per-user \Seen flag

location = maildir:/var/vmail/public/:CONTROL=~/Maildir/public:INDEX=~/Maildir/public +-

-+# Allow users to subscribe to the public folders.
subscriptions = yes
}+-

-+mkdir -p /var/vmail/public/.TestFolder
chown -R vmail:mail /var/vmail/public/.TestFolder
chmod -R 0755 /var/vmail/public/.TestFolderou +-

ln -s /var/vmail/vmail1/domain.com/p/u/b/public-20160714100502/Maildir /var/vmail/public/.PublicMailbox

doveadm acl set -A "Public/TestFolder""user=postmaster@test.com" lookup read write write-seen write-deleted insert delete expunge create

# doveadm acl get -A "Public/TestFolder"~/pre~

• creating a symbol link to this maildir path like below
• set proper ACL with -+doveadm acl+- (check steps above)