(sorry, I don't post often and not quite sure how quotes work)
This is so true. I had an ex-boyfriend decide to start contacting me 5 years after we broke up. We had not been in contact since then, and he just suddenly started sending threatening messages and leaving threatening voicemails. He sent pictures with a gun. It scared the **** out of me. But, I didn't block him and let them continue because I needed them for the proof to obtain a restraining order. I still have them all saved actually and this was a few years ago.
Luckily, they stopped and I haven't heard from him since. I moved last year, so hopefully he doesn't find me or ever do anything again, but this case just shows that I have no guarantee of that being the case. He could pop up at anytime in the future.