dovecot - Apr 2018 - sharing a folder with all users in a domain

Hello,

I'm wanting to make a shared folder that anyone in a domain can get
to, but not anyone in any other domain.

Here's my dovecot shared namespace:

namespace {
  type = shared
  separator = /
  prefix = shared/%%u/
  location = maildir:%%h:INDEX=~/shared/%%u
  subscriptions = no
  list = yes
}

The dovecot-dict-sql.conf.ext file has:

map {
  pattern = shared/shared-boxes/user/$to/$from
  table = user_shares
  value_field = dummy

  fields {
    from_user = $from
    to_user = $to
  }
}

map {
  pattern = shared/shared-boxes/anyone/$from
  table = anyone_shares
  value_field = dummy

  fields {
    from_user = $from
  }
}

and in my global acl file I have:
shared/office@ user at domain.com lrwstipekxa
 shared/office@ user2 at domain.com lrwstipekxa

Thanks.
Dave.