Chapter 7 Firewall for FortiOS 5.0 : Firewall objects : Security profiles : Proxy Option Components
  
Proxy Option Components
Any time a security profile that requires the use of a proxy is enabled the Proxy Options field will be displayed. Certain inspections defined in security profiles require that the traffic be held in proxy while the inspection is carried out and so the Proxy Options are there to define the parameters of how the traffic will be processed and to what level the traffic will be processed. In the same way that there can be multiple security profiles of a single type there can also be a number of unique Proxy Option profiles so that as the requirements for a policy differ from one policy to the next you can also configure a different Proxy Option profile for each individual policy or you can use one profile repeatedly.
The Proxy Options refer to the handling of the following protocols:
HTTP
HTTPS
FTP
FTPS
IMAP
IMAPS
POP3
POP3S
SMTP
SMTPS
DNS
IM
NNTP
The configuration for each of these protocols is handled separately.
It should also be noted that these configuration apply to only the Security Profiles Proxy-based processes and not the Flow-based processes.