I have a php file that sends mail using the mail() function. The problem is one of the forms sends to a domain that is registerred on my server while having the mail handled on a different server. Postfix looks locally only. When it doesn't find the email address is rejects the message. How can I configure postfix to send mail to all domains through the internet and not locally?

Update

Ok. So it wasn't a postfix issue at all. I simply needed to turn off mail to that domain from the command line. For anyone that needs that command it is (at least on my system):

/usr/local/psa/bin/domain --update example.com -mail_service false