Prevent dovecot logins while host != originalHost

roles/mail/templates/auth-server/dovecot.yml.j2

@@ -3,7 +3,7 @@ dovecot:
     - backend: ldap
       params:
         search_base: "uid=%s,ou=People,dc=investici,dc=org,o=Anarchy"
-        search_filter: "(status=active)"
+        search_filter: "(&(status=active)(host={{ shard_id }})(originalHost={{ shard_id }}))"
         scope: "base"
         attrs:
           email: uid