4164 Redirected parcel post packages. Exchange post offices. Registration of cor- respondence. Prepayment on par- eel post packages. INTERNATIONAL AGREEMENTS OTHER THAN TREATIES [61 STAT. (f) Articles of every kind not prepaid or insufficiently prepaid, originating in either country and addressed to the other, shall be dealt with in accordance with the regulations prescribed by the Universal Postal Union Convention in force for unprepaid and insufficiently prepaid articles. Article 3 In case a parcel post package is redirected from one address to another in the country of destination, it shall be subject to an addi- tional charge for postage. The country of destination may, at its option, levy and collect from the addressee of a parcel post package for interior service and delivery, a charge, the amount of which is to be fixed according to its own regulations, but which shall in no case exceed five cents for each parcel regardless of weight. A customs clearance charge may also be collected on each parcel post package which may in no case exceed ten cents for each parcel. Article 4 (a) Exchanges of mails under this Convention shall be effected through the post offices of both countries designated as exchange post offices under such regulations relative to the details of the exchanges as may be mutually determined to be essential to the security and expedition of the mails and the protection of the customs revenues. (b) Each country shall provide for and bear the expense of the conveyance of its mails to the other. Article 5 (a) Any packet of mailable correspondence, with the exception of parcels prepaid at parcel post rates, may be registered upon payment of the rate of postage and the registration fee applicable thereto in the country of origin. (b) An acknowledgment of the delivery of a registered article shall be returned to the sender when requested; but either country may require of the sender prepayment of a fee therefor not exceeding ten cents. Article 6 Ordinary and registered exchanges shall be effected in properly closed sacks, under such regulations relative to the details of the ex- changes as may be mutually determined to be essential. If a registered article advised shall not be found in the mails by the receiving office, its absence shall be immediately reported by the receiving to the sending office. Article 7 (a) All parcel post packages must be fully prepaid before dispatch. Parcels which are not delivered for any cause, shall be reciprocally returned without charge, through the appropriate exchange offices of the two countries, after the expiration of the period for their detention prescribed by the laws or regulations of the country of destination. Such parcels shall be liable on return to senders to a charge equal to
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