Chapter 1 What’s New for FortiOS 5.2.1 : Authentication : User Authentication via a POP3 Server
  
User Authentication via a POP3 Server
A POP3 server can now be used to verify user credentials when they authenticate through a web portal or any supported authentication method.
The following maximum values are associated with POP3 authentication:
1. A maximum of 10 pop3/pop3s servers can be defined per box
2. A single user group can have up to a pool of 6 POP3 servers assigned
POP3 authentication can be configured using the CLI:
Configuring a POP3 user
config user pop3
edit name
set server "pop3.fortinet.com"
set secure {starttls | pop3s | none}
set port 110
end
end
Configuring a POP3 user group
config user group
edit pop3_grp1
set member "pop3_server1" "pop3_server2"
end
end