These instructions relate to Outlook Web App.
Message Detailsicon on the toolbar at the top of the message and click on it.
Figure owa1.png [Toolbar, showing row of icons. 'Message Details' is a small envelope with a letter in front.]
Message Detailsbox opens and you will find the header under the
Internet Mail Headers
Figure owa2.png [Message details displayed]
<CTRL A>followed by
<CTRL C>) and paste it into an email which you send to email@example.com.