Usually, those types of letters came with some form of fictional story that was usually in a horror genre or something else, as they would indicate that a ghost would come to haunt them or something else if they failed to pass it on to another in a certain number of days.
There was a time when they were passed on quite regularly, but like most things, the interest toward them soon faltered, and people stopped sending them if they received them.
They started to become more of a nuisance for many people, so it would not be strange that the things Ash had sent would be mistaken for such a thing.
To other people, it could seem like quite an elaborate chain letter or something similar, especially with how there were a lot of things mentioned that could only be believed to be some form of supernatural ghost story meant to scare them.
Others would just as easily think that it was a joke that someone they knew had set up.
