that's system working as intended.

SPAM is officially described as UCE, "Unsolicited Commercial Emails". Your emails are both unsolicited and commercial, so people rightfully block it. I know I always click "report spam" when I see an unsolicited commercial email, not just to clean my inbox ("report spam" and "delete" are right next to each other), but to make sure sender's reputation takes a hit and fewer other people get spam email.