Official marks to be prima facie evidence of certain facts denoted
87.  In any proceedings for the recovery of any postage or other fee or sum payable under this Act in respect of a postal article —
(a)the production of a postal article having thereon the official mark of the Corporation 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.