That sounds very scary- I'm glad he didn't have any overtly malicious reason for it. What did the letter say? Was it a "hi date me" type of thing?
Yes, it was essentially a love letter ending with “please call me“.
I actually did text him - since he included his phone number and I wanted to know who he was - but I “ghosted“ him after some months when he kept asking me to come to his home (he was twentysomething so several years older than me).
Afterward, I received one more postcard from him telling me how much he misses me and how he wished I was there with him (he was travelling at that time) but then it stopped.