Unable to relay a message

Hi,

I’m having a problem with my SMTP server. We are developing a web based application (using .Net) that requires sending mail to the internet. Using the computer generated mail, sending the mail internally is successfull. But when the mail needs to be sent out to the external domain (yahoo.com, gmail.com, abc.com), it was rejected by the SMTP server with message “Attempt to relay mail [192.168.10.100] rejected for policy reason.” While browsing the net, I found one article that suggested to add my own ip address in the Configuration Document > Router/SMTP > Restriction and Control > SMTP Inbound Controls > Inbound Relay Enforcement > Exclude these connecting hosts from anti relay checks. I took my time to try it out but still, it didnt work for me. Instead, after test it out, I got another message on the console, “Message not routed to recepient abc@abc.com for policy reasons”, and followed by “Policy Reason: Router: myname@mydomain.com is restricted from sending mail through server SMTP/SVR/MYDOMAIN”. For your information, my server is not loaded with POP3 or IMAP. I need to release those computer generated mail to the internet. Please advise accordingly. Thanks in advance.