thahir, Welcome to McAfee community.
Are you using McAfee Site Advisor? If your resources permit, please look in to our McAfee Web Gateway | McAfee Products . It is more robust web proxy.
Now, if you want to use SiteAdvisor, you certainly can. In order for that to work, I hope your system tree is well organized. But you can also create "tags" as well. The most important thing is that you have to create custom Site Advisor policy. You want to create "Prohibit List" policy for Site Advisor. This is where you define the action. Once you've crafted your policy, you then need to assign to appropriate groups/departments. If all marketing or IT teams are already in separate folders in system tree, you can assign the policy on folder level. The other alternative is "tagging" the systems as needed, then attach the policy to systems with that tag. Look in to ePO menu | Policy | Policy Assignment Rules.