Absurd amount of Email Spam

When it comes to email spam. It usually comes from a few sources. Which are easy enough to filter out then they try a new one a few days later. Recently though and this one is rather insidious cause no matter how many filter methods I've tried to date and I've tried a lot nothing seems to work. I'd load up a video game  play for like 6 hours log out. Check my email then see like 12 Emails to my secondary email. And I have no idea how they got it. I checked my computer Malware, Virus it's clean. targetnews@mypentax.com That's the most recent set of email spam that I've been getting. Not sure what it is or how they got my email. I just want it gone.