65.  In any proceedings for the recovery of any postage or other charge alleged to be due under this Act in respect of any postal article -

(a) the production of the postal article having thereon the official mark of the licensee or the signature of an employee of the licensee denoting that the article has been refused, returned unopened or unclaimed, or that the addressee is dead or cannot be found, shall be prima facie evidence of the fact so denoted;

(b) the person from whom the postal article is supposed to have come shall, until the contrary is proved, be deemed to be the sender thereof; and

(c) the production of the postal article, having thereon the official mark of the public postal licensee denoting that any postage or other charge is due in respect thereof to the operator or to the postal administration of any foreign country, shall be conclusive evidence for all purposes that the sum so denoted is due.