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.
Sans looking, for I'm ready to hit the hay, I think I have a copy of that dump.