A local policeman came to take my report today and took the letter away. He asked if I needed it and of course I said no, I saw no need to ever see it again. I did not take care to avoid fingerprints on the letter (because I didn't initally think I would be turning it over to the police, or that they would take it as seriously as that) so I was advised that if I get another one, to avoid getting prints on it.
The nice patrolman did correct me; technically it's harassment, not hate mail, since it didn't specifically name or threaten me in the contents. I appreciate the correction but it doesn't make me feel a whole lot better. A little bit, though; "harassment" is a slightly less noxious word than "hate."
And life goes on.