Modifying this control will update this page automatically
Show detailed headers in Mail on Mac
When you view an email message, you can show more fields in the message header, such as List-ID or Resent-From.
In the Mail app on your Mac, choose View > Message > All Headers.
To view fewer header fields again, choose View > Message > Default Headers.
You can specify additional fields to show in default headers in Viewing settings in Mail.