The rollout for Sign in with Apple was a disaster when it came to email deliverability. They seem to have given zero thought to people who used third party emai

The rollout for Sign in with Apple was a disaster when it came to email deliverability. They seem to have given zero thought to people who used third party email services like CustomerIO or Sendgrid, indicating that they "weren't supported," leaving those providers to scramble to meet the strict DKIM / SPF / Return-Path requirements. Not only that, but if you were sending from an appropriately aligned and verified domain, in the first couple of weeks, deliverability might take in upwards of 12 hours for receipt. I believe they've since improved on the deliverability and the third-party email providers have accommodated appropriately, with Apple even providing brief integration tips for the most popular ones, but it left a pretty horrible taste in our mouths as we were jumping through all the integration hoops. EDIT: This is referring to email deliverability when attempting to contact private Apple relay addresses.