You really never know how people will respond to having their past thrust at them like this. Or how they'll respond to strange phone calls.I've bought many books over the years that had prior owner's names marked inside somewhere. On a few occasions I've bothered to try and identify/find the person in question. Once or twice I was successful, but I never bothered contacting them just to say "Hey, I bought this book you used to own". Well, except for one time.
I was on an Inductive Logic Programming / Prolog kick, and bought several used books on the subject. Something like two or three had all been owned by the same previous owner. I looked him up and found out that he was an academic and appeared to still be working, so I thought "what the heck" and sent him a note just to say "Hey, funny story, I bought these books and ."
Not sure what I expected, if anything, in return, but the response I did get was quite chilly. It was something along the lines of "Oh, I donated those to a place that was supposed to be sending them to Africa" or something like that. There was definitely no sense that this individual was happy to hear from the new owner of his old books, or was interested in discussing the subject.
Which is fine. Like I said, I had no idea what to expect, and certainly would have had no right to expect any particular response. But it just goes to show... you are correct in saying
"You really never know how people will respond to having their past thrust at them like this. Or how they'll respond to strange phone calls." (or strange emails in this case)