The international transportation of mail is governed by the rules and regulations developed by the Universal Postal Union (UPU). The rules and regulations are laid down by the Universal Postal Convention.
- Mail must be contained in closed dispatches (envelopes, bags) properly listed on appropriate documents, except such parcels which may be delivered open.
- Each mail bag must be provided with a tag, applicable to mail type in question, showing the dispatch number, office of origin and destination, airport and the weight of the various categories of mail.
- Post office is responsible for checking that:
- Mailbags, packages, envelopes etc. are in good condition, correctly labelled and sealed.
- Mail delivered conforms to the accompanying documents.
- Damaged mail is not accepted for transport and it will be returned to post office.