Mail (Yosemite): Show detailed message headers

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When you view messages, you can show more fields in the message header, such as List-ID or Resent-From.

Show the headers: Choose Mail > Preferences, click Viewing, then select “Show additional message headers.”

Change the headers that are shown: Click Select Headers. To delete a field, select it, then click Remove . To add a field, click Add , then enter a field name.

Published Date: Sep 15, 2017