1. Open your Outlook 2013/2016
  2. Double click on a message to open it.
    Email
  3. Navigate to the horizontal menu at the top. Click on 'File'.

    File

  4. Click on 'Properties' in the 'Info' section.

    Info

  5. Copy the text in the field named 'Internet headers' - this is your message’s mail header.

    Headers