When our team integrate Sign in with apple function, we met some trouble. As some other people mentioned,We also can not send email to apple relay with our personal email list in Developer Portal.
We don't know why? Please help us to fix it. Following are error infomation.
Diagnostic-Code: smtp; 550 5.1.1 Relay not allowed for XXXX@privaterelay.appleid.com. from domain<our domain>