The problem lies with the big e-mail providers marking your e-mail as spam, even if you have everything configured right (MX, SPF, DKIM, DMARC, etc.) and you're not on any blacklists. They use their mysterious opaque algo to determine that your e-mail is spam and you have no idea what you could do to not get in peoples junk boxes.
The problem lies with the big e-mail providers marking your e-mail as spam, even if you have everything configured right (MX, SPF, DKIM, DMARC, etc.) and you're not on any blacklists. They use their mysterious opaque algo to determine that your e-mail is spam and you have no idea what you could do to not get in peoples junk boxes.