Subsection (2) applies to—
a postal packet,
anything contained in a postal packet, and
a mail-bag containing a postal packet,
which is not the property of the Crown but which is in the course of transmission by post.
Anything to which this subsection applies shall have the same immunity from—
examination, or seizure or detention, under a relevant power conferred by virtue of this Act or any other enactment,
seizure under distress or in execution,
in Scotland, any diligence, and
retention by virtue of a lien,
as it would have if it were the property of the Crown.
In subsection (2) “relevant power” means any power other than—
a power conferred by section 47 so far as it is exercised for any purpose connected with the investigation of an offence under section 6 or any proceedings for such an offence,
a power conferred under section 49,
a power conferred by an enactment relating to customs or excise in its application, by virtue of section 105 or any regulations made under that section, to goods contained in postal packets, or
a power conferred by section 106 or 107.
The Secretary of State may by order modify subsection (3).
Subject as follows, the enactments for the time being in force in relation to customs or excise shall apply in relation to goods contained in postal packets to which this section applies which are brought into or sent out of the United Kingdom by post from or to any place outside the United Kingdom as they apply in relation to goods otherwise imported, exported or removed into or out of the United Kingdom from or to any such place.
The Treasury, on the recommendation of the Commissioners of Customs and Excise and the Secretary of State, may make regulations for—
specifying the postal packets to which this section applies,
making modifications or exceptions in the application of the enactments mentioned in subsection (1) to such packets,
enabling persons engaged in the business of a postal operator to perform for the purposes of those enactments and otherwise all or any of the duties of the importer, exporter or person removing the goods,
carrying into effect any arrangement with the government or postal administration of any country or territory outside the United Kingdom with respect to foreign postal packets,
securing the observance of the enactments mentioned in subsection (1),
without prejudice to any liability of any person under those enactments, punishing any contravention of the regulations.
Duties (whether of customs or excise) charged on imported goods or other charges payable in respect of postal packets to which this section applies (whether payable to a postal operator or to a foreign administration) may be recovered by the postal operator concerned and in England and Wales and Northern Ireland may be so recovered as a civil debt due to him.
In any proceedings for the recovery of any charges payable as mentioned in subsection (3), a certificate of the postal operator concerned of the amount of the charges shall be evidence (and, in Scotland, sufficient evidence) of that fact.
In this section “foreign postal packet” means any postal packet either posted in the United Kingdom and sent to a place outside the United Kingdom, or posted in a place outside the United Kingdom and sent to a place within the United Kingdom, or in transit through the United Kingdom to a place outside the United Kingdom.
A postal operator may—
detain any postal packet if he suspects that it may contain relevant goods,
forward any packet so detained to the Commissioners of Customs and Excise.
In this section “relevant goods” means—
any goods chargeable with any duty charged on imported goods (whether a customs or an excise duty) which has not been paid or secured, or
any goods in the course of importation, exportation or removal into or out of the United Kingdom contrary to any prohibition or restriction for the time being in force by virtue of any enactment.
Subsection (1) is without prejudice to section 105.
The Commissioners may open and examine any postal packet forwarded to them under this section—
in the presence of the person to whom the packet is addressed, or
where the address on the packet is outside the United Kingdom or where subsection (5) applies, in the absence of that person.
This subsection applies where—
the Commissioners have—
left at the address on the packet notice requiring the attendance of the person concerned, or
forwarded such notice by post to that address, and
the addressee fails to attend.
If the Commissioners find any relevant goods on opening and examining a postal packet under this section, they may detain the packet and its contents for the purpose of taking proceedings in relation to them.
If the Commissioners do not find any relevant goods on opening and examining a postal packet under this section, they shall—
deliver the packet to the addressee upon his paying any postage and other sums chargeable on it, or
if he is absent, forward the packet to him by post.
If a postal operator knows or reasonably suspects that a postal packet is being sent by post in contravention of section 85, he may—
refuse the transmission of the packet,
detain the packet and open it,
subject to any requirements as to additional postage or charges, return the packet to its sender or forward it to its destination,
destroy or otherwise dispose of the packet.
Subsection (1) is without prejudice to any other powers which the postal operator may have in relation to the packet (whether under the terms and conditions applicable to its transmission by post or otherwise).
The detention or disposal by a postal operator of any postal packet on the grounds of a contravention of section 85 or of any terms and conditions applicable to its transmission by post shall not exempt the sender from any proceedings which might have been taken if the packet had been delivered in due course of post.