I set up a site on my staging server, used both my email address and the customer's to test the commerce module order emails and everything worked just great. Even though the staging server was xyz.com I could get those emails at me@abc.com and customer@def.com.
When I moved the site over to their IIS server (with apache, php, MySQL installed), I can't get the emails from customer's site def.com to go to any email address at def.com. I can, however, get those emails to come to my email at abc.com
Their sys admin's reply is: "Well the first thing that comes to mind is how the smtp server is configured for the commerce_kickstart module. I can't easily get at that. If its set to a @def.com address then it might try to send like emails locally and they would fail."
Is this a site config, Commerce config or server config I need to be looking for?
Thanks!