Official marks to be prima facie evidence of certain facts denoted
66. In any proceedings for the recovery of any postage or other fee or sum payable in respect of a postal article —
(a)
the production of a postal article having thereon the official mark of a public postal licensee denoting that the article has been refused or that the addressee is dead or cannot be found shall be prima facie evidence of the fact so denoted; and
(b)
the person from whom any postal article purports to come shall, until the contrary is proved, be deemed to be the sender thereof.