I had installed q mail in a system with Local ip 192.168.1.142 which is behind a firewall configured with static ip. I am able to recieve mails but when i try to send email following error message is recieved. Please help...

Hi. This is the qmail-send program at localhost.localdomain.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.