We have registered the full email addresses on the developer portal and they have green ticks next to them.
We are using SendInBlue as an email service, and we are using our own domain+dedicated_ip. With all SPF and DKIM configurations also done and verified.
Problem is that 50% of the time - emails are not getting delivered to apple-relay-email-ids (the email ids which look like @private.appleid.com). So, sometimes works, sometimes doesn't without any error or info.
How can we debug of fix this?