I get a bazillion of them, I have 5 email accounts, I use one of them for SR, on for CR/QR and I get crap like that in all of them. The only account I have never gotten any junk mail in is GMail, and I had used that address at CD, although I never did anything at that site. When a spammer decides to send out his great stuff, he has a bot do it,they pick an email supplier, like yahoo.com and then just start sending out to any combination of names. So maybe you have
lssmith@yahoo.com, the bot will send to asmith, absmith, etc till it uses every possible combination of letters before smith. Or it will use lsmithe, lsmithd, etc. If you have ever used your email at any web site, a crawler can intercept it, too. Sadly, there is almost no way of getting around spam. I am amazed that we NEVER get any at work. My husband works for a German company, they can not stop the spam on thier servers and he gets at least 200 a day!
Just be glad most go to your junk folder and report the ones that don't. Since yahoo instituted the auto filers, I get very few in my inbox there, but plenty in the junk. If you are using outlook mail, you can also block many of them.
Good Luck.