We have a website which validates users by making sure that they come through a link from the company's secure site. This is done by checking the Refering URL. This works most of the time but for some users we are getting a blank Referring URL, although they are coming through the valid link. Any suggestions as to what could be causing that. Does some firewall setting, or other software installed on clients machine may cause not to pass the referring URL correctly?
Thanks in advance for your input.