Chapter 15 Unified Threat Management for FortiOS 5.0 : Security Profiles overview : Content inspection and filtering : FortiGuard Web Filtering : FortiGuard Web Filtering recommendations
  
FortiGuard Web Filtering recommendations
Enable FortiGuard Web Filtering at the network edge.
Install the FortiClient application and use FortiGuard Web Filtering on any systems that bypass your FortiGate unit.
Block categories such as Pornography, Malware, Spyware, and Phishing. These categories are more likely to be dangerous.
In the email filter profile, enable IP Address Check in FortiGuard Email Filtering. Many IP addresses used in spam messages lead to malicious sites; checking them will protect your users and your network.