Illegal use of mail slot

What is the name of your state?What is the name of your state? Oregon

In this extremely contentious political season I received a "letter" filled with propaganda from a campaign for a ballot measure here in the state. It was unstamped, unmailed, though in a sealed envelope and received through my mail slot in my apartment. Isn't this illegal? The mail slot is for use by the postal service only, I thought. Please advise.

You can contact the local postmaster, but chances are nothing is going to happen. While they shouldn't be doing this, I have never heard of this sort of thing being prosecuted.

- Carl