OUTLOOK POP3 DOES NOT WORK USING ISA SERVER

Hi
I have installed  Isa 2006 in win2003 and all clients can browse internet but they cannot send or receive emails through outlook 2003 and 2007.

The following is my cards cofiguration
Internal
IP ADDRESS   192.168.1.132
sub mask        255.255.255.0
gateway         no gateway here
DNS                192.168.1.132
----------------------------------------
External
IP ADDRESS  192.168.5.131
SUB MASK    255.255.255.0
GATEWAY   192.168.5.55  ----------  MODEM
DNS              84.235.1.22  -----------  ISP provide this
DNS              192.168.1.103 ----------- MY network DNS
------------------------------------------------------------------------
I created rule to allow pop3,pop3 server,smtp,smtp server ,nntp  (as first rule after default deny)
i created rule to allow dns then http.
I change  oulook.exe from 1 to 0
I have installed also firewall client in client machine but cannot connect.
still i cannot use outlook for my mails