Open the Exchange Management Console, and navigating through the console tree to Organization Configuration | Hub Transport. Next, click to the New Send Connector link
To send mail to the outside world, choose the Internet option from the drop down list.
Click Next, and you will be taken to a screen that asks you to specify the address space to which the connector will route mail.we will use an asterisks in place of an address space to specify any SMTP servers.
Click Next, and you will see a screen asking you if you want to use DNS MX records to route the outbound SMTP mail automatically, or if you would prefer to route mail through a smart host.
Select use DNS MX records to route the outbound SMTP mail to send mail to outside world. Select Smart Host routing if you want your mail to route to any of your SMTP servers.
Click Next, Exchange must bind the send connector to a specific hub transport server in your Exchange organization. By default, Exchange chooses the server that you are creating the connector.
Click Finish and Create new Send Connector.