We don't have static Ip addresses nowadays either, they change.
I have an email which has been used for nothing, absolutely nothing. It's a professional email I use just for the volunteer role I partake in with children. To contact parents, etc.
It's been spammed. Why? A not so savvy parents email got hacked, they harvest email contacts and bam. That's what happens Freda, if you click links in these emails. You get hacked and phished, then they target your contacts.
All of a sudden I'm looking for Viagra, hot Russian girls, Christian dating, yadda, yadda, yadda.
It is literally as simple as a third party being hacked and your email being passed on, or you agreeing to it with third party ticks. Then it goes on and on! It just means your email is out there!