Earlier quoted context omitted.
Gmail blocks my mailserver, I recently discovered it’s the lack of ipv6 that causes it.
If your mail server is in AWS, it's not ipv6 that is the problem per se. It's that google has blocked the entire AWS address space. To be fair, you shouldn't be sending email from AWS without going through SES, which has it's own address space and has specific deals for deliverability to all the big mail recipients, like gmail and hotmail.
Please provide citations if you’re going to speak so factually.