Why are my emails to `@privaterelay.appleid.com` addresses failing and causing a high bounce rate?

If you are experiencing a high number of hard bounces from email addresses ending in @privaterelay.appleid.com, it is because your sending domain has not been authorized to send emails through Apple's Private Email Relay service.

What is Apple's Private Email Relay Service?

When users sign up for your service using "Sign in with Apple," they have the option to hide their personal email address. Apple then generates a unique, anonymous email address for them (e.g., example@privaterelay.appleid.com) that forwards messages to their real inbox.

Why are the emails bouncing?

To prevent spam, Apple requires that you register and authorize any domain you use to send emails to these private relay addresses. If your sending domain is not authorized, Apple's servers will reject the email with an "unauthorised sender" error. This rejection is treated as a hard bounce, which can negatively impact your sender reputation and may lead to the automatic suspension of your email platform if the bounce rate exceeds the allowed threshold.

How to fix this issue

To resolve this, you must configure your sending domains to be compliant with Apple's service. Please follow the official instructions provided by Apple in their developer documentation:

• Communicating Using the Private Email Relay Service

After you have successfully authorized your domain with Apple, your emails to these private relay addresses should be delivered successfully, and your bounce rate should return to normal.