Nah, I run my own email servers - definitely not found by guessing - I'd see the other attempts.
However, it is the same email I've had here for 5 years, but the first time I've had spam sent to it.
If you have had the email on your bitcointalk profile (even hidden counts), than it was probably in the forum data breach from 2015. I don't think it was very easily obtainable/required a payment to get it until recently, since I've noticed that sites like leakedsource have added the database. I suggest searching your email up in
https://www.leakedsource.com/ and see if it is from that leak.
I think this is likely the source if he had it so long. As I don't know if we really know what they did with the DB at this point. I remember them logging into inactive accounts like Mt. Gox and such trolling.
At the time I was curious how much info they got and mentioned something about them being a scypt kiddie or something in META and asked to impress me and give my IP. They were able to do it at the time.... So I don't know what all data got out but know my IP at the time was part of it. I hope no new hacks like that one have happened.