Note:  The instructions below were attained with using a McAfee Web Gateway v6.8.7 build 7612

For those of you using McAfee Webwashers as one of your levels of web filtering and security, you may or may not have realized that white listing websites that the WW  is blocking access too is pretty cut and dry.  At least it was for me.  However, when a client administrator asked me to blacklist or block a website that was undesirable by management I had to scratch my head.  Below are those steps to blacklisting if you have not figured it out yet.

1.  Log into the McAfee WebWasher web interface
2. Navigate to the URL Filtering tab
3. Verify you have the correct security policy selected for which you want to edit the rules.
4. Select Filter by Expression option to the left
5. Underneath the Expression List option you can input the domain name (example:  yahoo.com) for which you want to block access from. 
6. Leave String value default option selected
7. Fill in a short description of the website’s credentials
8. Check the box “Add to All Policies” if you would like to add the blocked site to all security policies or not.
9. Select the Add button

That’s it.  At this point any user falling under the policies you modified will not be able to access the site with domain name you specified.