Ok i'm trying this and still no luck.
Here let me describe how i'm setup.
My main forward chain has a rule;
Any source, destination any, going out on SERVER port with any protocol and any connection state,,, JUMP TO -> Server_Rules Chain.
Ok is this clear?
Now!, in the Server_Rules chain i have rules for all the ports that i want to allow access to these servers e.g. (25,20,21,80,110,143 and such) then last rules is reject everything.
Now i've tried putting a rule like you said in there to allow extablished connections and this did not work, the BYTES and PACKES don't even move.
I'm still in the dark