Viewing the full header of an email is necessary if you wish to trace the IP address or want more information about the email you have received like bounce back emails. Follow the instructions from this article on how you can view it with Webmail.
Step 1. Login to Webmail and choose SquirrelMail.
Step 2. Choose on Inbox or any folder where the email is.
Step 3. Open the email you want to view the full header.
Step 4. Click on View Full Header link in Options.
Step 5. You will be redirected to a page where it will show the full header of the email.