Log on to Forefront TMG Server, Browse to %Program Files%Microsoft Forefront TMGerrorhtmls . Copy default.htm file and paste inside a folder called banned. Now modify the file using Microsoft Office word and add corporate logo and notice. Once you have modified this file, it will automatically create a folder named default_files containing this logo files. Now in an IIS server, copy the banned folder to %windir%inetpubwwwroot to publish a website that will be sub-domain to your domain for example http://banned.microsoftguru.com.au .
If you do not want sub-domain then you can publish this site as http://yourdomain.com.au/notice . For this article, i am going to publish custom error url as sub-domain.
Log on to an IIS server. right click on IIS server, Click Add web Site, Type Site Name, Point Physical Path as shown on the picture. In the host name, type FQDN of the web site. You don’t need to create a separate web server to do this you can add web site to an existing web server.
Log on to DNS server, Open DNS management console, right click on forward lookup zone, add CNAME
Log on to Forefront TMG server as an administrator, click Networking, right click on internal network, click on property, click on web browser, check Bypass proxy for web servers in the network.
Apply changes and click ok. Open internet explorer and test newly created website.
From the TMG console, click web access policy, In the Tasks Tab, click on configure web access policy,
Here, cache drive shown in system partition, however in production environment setup cache drive in separate partition.
Right click on newly created deny policy, click on property, click on action tab, on the redirect web client box type custom url to redirect users.
To test this policy, log on to a computer using a test username and browse any website classified in the banned category. you will be redirected to new website as follows.