Dear all, I have ISA machine sit with a dialup connection to an ISP. All web proxy request from cliets are routed to the Internet without problem. Linux is a single machine on the our network and having sendmail server installed. Senmail have configured to use ISP's SMTP service to send all outbound messages to the Internet users. Does anyone know what steps are involved within ISA to allow a SecureNAT as mentioned above to pass through? Many thanks in advance, Sothun PS. I have gone through the SecureNAT client topic but there is no specific steps.