How to view complete email header in Webmail :Horde and RoundCube.
Horde Webmail :
1) Login to Webmail using the URL (http://domainanme/webmail)
2) Click Open to on Read Mail Using Horde

3) Double click on the email that you wish to view the header for
4) Then click on " View Source " on the top right panel

5) You are then able to view the complete email header of the email
Roundcube Webmail :
1) Login to Webmail using the URL (http://domainanme/webmail)
2) Select on Read Mail Using RoundCube

3) Double click on the email that you wish to view the header for
4) Click on the option "More" and "Show Source"

5) You are then able to view the complete email header of the email