This article will outline the steps to view the full email header in both Horde Webmail and Roundcube webmail
Please select either Horde or Roundcube.
Part 1 -->Horde
Part 2 -->Roundcube
This section will guide you through the process of viewing the complete email header in Horde Webmail
1) Log in to Webmail using the URL (http://yourdomain.com/webmail)
2) Click on Horde.
3) Click on the Open button.
4) Double click on the desired email.
5) Then click on View Source located at the top right of the popup window displaying the email content.
6) You will now be able to view the complete email header of the message.
This section will demonstrate how to view the complete email header in Roundcube Webmail
1) Log in to Webmail using the URL (http://yourdomain.com/webmail)
2) Click on RoundCube.
3) Click the Open button. 
3) Double click on the email for which you want to view the header
4) Click on "More" → "Show Source"
5) You will then be able to view the complete email header of the message