· metal containers, such as ammunition boxes, are not used as letterboxes. This is at the request of the Ministry of Defence, because metal containers may become confused with potentially dangerous military debris.
· Letterboxes are placed only in existing natural holes or cavities. Under the by-laws it is an offence to damage land.
· you try as far as possible to position your letterbox at a distance from other existing letterboxes.
· Letterboxes are not cemented or in any other way permanently fixed in place.

For all letterbox hunters, please ensure that:
· you search for the letterbox in a way which does not damage or disturb the land. Do not lift rocks or remove stones from walls.
· you replace the box carefully and leave it as you would hope to find it.
· if you find a box in need of attention, for instance if it is saturated, you contact the owner and/or the Letterbox 100 Club who will report the fact in their fortnightly update.
· you do not search for letterboxes:
If you do find any letterboxes that contravene this guidance please act responsibly and notify the box owner, explaining the circumstances. Help keep letterboxing a Dartmoor friendly pastime!