Abstract: An electronic frank, e.g. electronic stamp, in use arranged to be associated with data to be transmitted over a telecommunications network (405) to an intended recipient at a destination address (408), the electronic frank comprising a data structure containing a set of at least one authenticated parameter-value, each parameter-value associated with a characteristic of the data to be transmitted, the data structure arranged in use to be processed by an apparatus (406) arranged to forward the data towards the intended recipient it is transmitted over the telecommunications network, whereby the apparatus is able to determine from the contents of the data-structure if the electronic frank conforms to at least one predetermined criteria prior to the data being transmitted to the destination address.