The Anti-Spyware and Anti-Malware service displays the Insight block page instead of the requested webpage when the Insight reputation service detects potential malware. You can use the default message to tell users why they cannot view a webpage, or you can enter a custom message.
To customize the Insight block page message
The Insight reputation service, which is included with the Web Anti-Spyware and Anti-Malware service, blocks known threats. If a requested file download looks somewhat suspicious, but not suspicious enough to block, Insight does further analysis after the download. If the analysis determines that the file is potential malware, Insight can send email notifications to up to five recipients.