P.P.S. Iwas thinking about this again and it is probably not possible to support this combination: dot separator + shared mailboxes + usernames with dots (including the domain part).
So I suggest update in the wiki: > n.b. If you have dots "." in your usernames (like `name.surname` or > `n...@example.com`) it is not possible to use dot as a [[Namespaces|namespace > separator]]. Don't forget to use `separator = /` in such cases. on http://master.wiki2.dovecot.org/SharedMailboxes/Shared