38 (2) The Authority may determine the conditions subject to which a postal licensee shall be entitled to use posting boxes erected or owned by another such licensee. 52 Provision of postage stamps (1) In this section⎯ “philatelic archival materials” include⎯ (a) philatelic stamps; and (b) artworks, proofs, progressive sheets, printed sheets and printing plates of philatelic stamps; and (c) date-stamps, slogan dies and other artefacts used in connection with the production of philatelic stamps. (2) Subject to this Act and any directions given by the Authority, a postal licence authorising the provision by the licensee of postage stamps may cause postage stamps to be provided of such kinds and denoting such values as the licensee may determine. (3) A postage stamp provided under this section shall be used for the prepayment of any postage or other sum chargeable in respect of any postal article, except where the postal licensee concerned determines that prepayment may be made in some other manner. (4) All philatelic archival materials produced by a postal licensee shall be kept in such custody as the Authority directs. 53 Official marks to be prima facie evidence of certain facts denoted 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 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. 54 Recovery of postage and other sums due in respect of postal services (1) Where any postage or other fee or sum is not prepaid or fully prepaid in respect of a postal article posted for delivery by a postal licensee, the postal licensee may refuse to deliver the postal article until the postage or other fee or sum has been paid to or recovered by him. (2) If any postage or other fee or sum has not been paid or recovered within six months of a written demand by the postal licensee made to the person liable to pay it, the licensee may dispose of the postal article in any manner described in paragraph (d) of subsection (1) of section fiftyfive, and paragraph (e) of subsection (1) and subsection (2) of that section shall, mutatis mutandis, apply to such disposal. (3) An official mark or label on a postal article denoting that any postage or other fee or sum is due in respect thereof to a postal licensee or to the postal authority of any foreign country shall be prima facie evidence that the postage or other fee or sum denoted is so due.