When service takes effect and proof of service
17.—(1)  In this Part, service of a document on a person takes effect —
(a)if it is sent to an email address — at the time that the document becomes capable of being retrieved by the person; or
(b)if it is sent to a postal address by prepaid registered post — on the second day after the day the document was posted (even if it is returned undelivered).
(2)  In proving service of any document sent by registered post to any person, it is sufficient to prove that the envelope containing the document was properly addressed to that person, stamped and posted by registered post.
(3)  In this regulation, “document” includes a form.