I can see that you posted Trim variables in environment on Sep’18 which makes your presence visible on this community support platform. Looking further, I can see your email address is visible on your profile.
It is widely used practice to scrape community support platform to scrape for email addresses and send targeted emails to users. I suspect this might be the reason you got spam.
We have set-up DMARC policies for all of our domains (and sub-domains) to protect our users from such SPAM attempts. We should get DMARC forensic report for further forensic if your email recipient server is configured to comply with DMARC policy. We will keep you posted with relevant information If we become aware of any other reasons.
Please do not hesitate to let me know if you have any other questions or concerns regarding this, or if you need further clarification, and I’ll be happy to further assist you.