Letterboxing Code of Conduct
Since the disaster of September 11th, security concerns are at unprecedented levels. Whether you are planting letterboxes or hiding them, consider the security ramifications of what you are doing—especially in urban locations.
Searching for letterboxes may look like 'suspicious activity' to someone that doesn't know what you are doing. The authorities have stopped and questioned such letterboxers. The best solution is simple: Don't look suspicious! Many letterboxers 'accidentally' drop one of their possessions so they don't look suspicious as they crouch down to pick it up. Others pretend to take pictures of each other with a camera—a good way to scope out a sign without drawing undue attention to oneself. Or have a partner cause a distraction somewhere else while you search for the letterbox. The possibilities are endless. Be creative!
Also, have a readily understandable excuse for what you are doing in case someone does challenge you. Tell them you're on a scavenger hunt. Tell them you were just sitting down for lunch and wanted to make sure there weren't any snakes nearby. You could even tell them the truth—that you are searching for a letterbox. It has the advantage of being honest, but most people have never heard of letterboxing, so it might require more explanation than you care to give. And if it's an authority figure, they might frown on letterboxing.
The best policy, of course, is to search for a letterbox when there's nobody around to see you doing it, and that should be your goal. It's not always possible, however, and it's up to you to always look natural and have a ready excuse—true or not—to explain what you're doing and why.
If you are planting a letterbox, paying attention to security concerns is even more important. 'Suspicious boxes' have been reported to the authorities and met their demise after being blown up by the bomb squad. While the authorities might be relieved to discover the box was not a bomb, they may not have been amused at the time and expense required to deal with the 'suspicious' box. Take measures to ensure your letterbox is not mistaken for something more sinister. Use small containers such as film-canisters that are less likely to be mistaken for bombs. Or use clear containers so people can see the contents from the outside and be assured there is nothing suspicious inside. Label the outside of your letterbox explaining what it is and provide contact information.
Even with all those precautions, common sense dictates that you do not hide letterboxes where security is at a heightened fervor such as in airports or near well-known national landmarks (Empire State Building, Golden Gate Bridge, Statue of Liberty, and so on). The FBI have even tracked down letterboxers for questioning.
Use common sense. We do not want to see you on the evening news being arrested nor do we want to see pictures of your blown up letterbox on the front page of a newspaper.