“Postal data” means data which—
(a) identifies, or purports to identify, any person, apparatus or location to or from which a communication is or may be transmitted,
(b) identifies or selects, or purports to identify or select, apparatus through which, or by means of which, a communication is or may be transmitted,
(c) identifies, or purports to identify, the time at which an event relating to a communication occurs, or
(d) identifies the data or other data as data comprised in, included as part of, attached to or logically associated with a particular communication.
For the purposes of this definition “data”, in relation to a postal item, includes anything written on the outside of the item.