Fully agree. I am in the same situation as you, and I even relay my emails through my ISP SMTP to avoid the issues such as 'residential IP marked as spammer'. A

Fully agree. I am in the same situation as you, and I even relay my emails through my ISP SMTP to avoid the issues such as 'residential IP marked as spammer'. And yet, Gmail will randomly classify simple personal emails. It is the only mail provider to act like this, I never had any issue with any other provider (ISPs, CSPs...) And to add insult to injury, they have this page: https://support.google.com/mail/answer/6227174?hl=en&ref_topic=6259779 https://support.google.com/mail/answer/6227174?hl=en&ref_top... but as I send too few emails, it is completely useless.