21.—(1) Any document that is to be served on any person in any proceedings before a tribunal or the Registrar must be served —
(a)
by delivering that document personally to that person;
(b)
by sending that document by registered post addressed to that person at —
(i)
that person’s last known residential address;
(ii)
that person’s registered address; or
(iii)
the address of that person’s principal place of business, as notified to ACRA; or
(c)
if that person is a party to those proceedings, and has been notified by the Registrar of that person’s right to access the electronic system to view any document served on that person in relation to those proceedings — as an alternative to serving that document in accordance with sub‑paragraph (a) or (b) — by submitting that document through the electronic system.
(2) Despite paragraph (1), a tribunal or the Registrar may, in any particular case, order that a document be served on a person by any other means that the tribunal or Registrar considers proper.