Microsoft have stop supporting all Internet Explorer browser versions.
There is a requirement to stop or deny users from using Internet Explorer browser when browsing the internet going through the proxy.
Below is the CPL that you could use to stop or deny all Internet Explorer browser versions from being used to browse the internet through the proxy.
define condition Block_All_IE
request.header.User-Agent="((?-i)MSIE [1-9]0?.\d+; Windows [^PC].*(\w\w-\w\w|P|T|U|;\s*|\d\w|\d(?<!WP\d))\)$)|(^Mozilla/\d+\.0 \(.*Trident/7.*rv:11.*\).*)"