Unsolicited Reference

Prior employee of a WI company. Left on my own - was not fired. Did not ask for a reference from that company. Got a new job in NY months after leaving prior company. My new employer told me today he got an unsolicited email from my prior employer stating all the "bad" things I did when in their employment with "i thought you would like to know" statement. The email sounded malicious. Even though the statements of events were technically true (and I did disclose all to my current employer before I was hired in my new job) - they were presented in such a way to make me look as bad as possible (which was not warranted under the totality of the facts). Can a prior employer just out of the blue be somehow trolling me and intentionally contact a current employer (unsolicited). I thought once I left our relationship was terminated. Thank you.