My first letterbox was placed within a few feet of a geocache. I had no way of knowing there was a geocache nearby. If the geocache is well-hidden, as it should be, then we don't know where they are and it's impossible to know if there is one near. Luckily, my brother (who is a geocacher) found my letterbox while he was looking for the geocache. I labeled the container "LETTERBOX" in large letters and left a note in the box about letterboxing. I put "THIS IS NOT A GEOCACHE. PLEASE DO NOT TAKE ANYTHING OR LEAVE ANYTHING" in large capital letters both in the note and on the container. Before I could get back to move the box, the stamp that I spent hours carving was gone and in it's place was a cheap plastic bracelet.
So, what is the solution here?
We have no way of knowing where your geocaches are, so it's impossible to avoid them.
We label the box.
We put notes in the box.
What else can we do?
Oh, and by the way, I've only been letterboxing since September of this year, but in the last 8 months, I have found 4 letterboxes missing and geocaches put in their place. Exactly in their place... as in, one of them was exactly behind the third brick on a bridge. I've also found 3 letterboxes vandalized and the stamp stolen. 2 of these had cheap swag placed in the boxes in place of the stamp. All of them were labeled and included a card with the URL of the letterboxing website.
There are several letterboxes that have simply gone missing. I do not blame the geocachers for this. It happens. A kid finds the box, someone who thinks it's trash throws it away, it gets carried away by animals, people steal them for whatever reason. BUT... when only the stamp is gone and a cheap trinket is left in it's place, what are we to think?