Postfix runs until reboot and can't find firewall
I recenly installed Mandrake 7.2. I installed a webserver and Bind. Everything worked, so I then configures Postfix (which came with Mandrake). Everything worked, I could send and receive mail. I then did a reboot and now I can only send mail and not recieve it. I diagnosed this as a firewall problem, but I can't find one if there is one installed. I have looked for the Tiny firewall, serched for files such as iptables and ipchains and nothing.
Can anybody help me?