Microsoft Exchange Relaying feature

While configuring SAP Connect with Microsoft Exchange server, SAP could send the mails to internal email addresses but couldn't send to email addresses out of domain. This is because of Exchange relay feature (quoting)
http://technet.microsoft.com/en-us/library/dd277329.aspx
"To allow specified IP addresses—internal or external—to relay, check the "Hosts and clients with these IP addresses" checkbox, then use the Add, Edit, and Remove buttons to build the list of IP addresses from which you want to accept relay traffic. Remember that this checkbox controls relaying when you have selected the radio dial for "Reroute incoming SMTP ..." in the Routing tab. You should normally check this box; doing so will prevent relaying. If you leave it unchecked, your server is open for relay."

But the confusion remained from normal IP address 192.168.1.x we can send mail to outofdomain email addresses but why not from SAP servers (because they are on 192.168.213.x IP range ) :-)

If the administrator wants he may allow the same (192.168.213.x) as well to relay to outofdomain email addresses.