A lot of Exchange administrators are surprised to learn that in most cases a new Exchange Server 2007 deployment is not able to send mail to the outside world until the administrator does some additional configuration. The reason for this is that unless you have installed an Edge transport server, and created an Edge subscription, Exchange Server 2007 does not create a Send connector.
As you probably know, hub transport servers use the SMTP protocol to send mail both internally and externally. All SMTP mail is routed through a Send connector. Exchange Server 2007 creates an implicit and invisible send connector that it uses to route mail between hub transport servers on your internal network. The reason why Exchange Server is able to create these implicit Send connectors is because it is able to compute the necessary requirements based on information that is stored in the Active Directory.
Unfortunately, Microsoft assumes that you are going to create an edge transport server at your network perimeter. Creating an edge transport server, and the accompanying edge transport subscription, causes Exchange Server to create a Send connector that can be used to transmit SMTP messages to the outside world. Like the implicit Send connectors, this connector is stored in the Active Directory. If you don't have an edge transport server though, then you will have to create the send connector manually.
Creating a Send Connector
Creating a Send connector is a fairly simple task. Begin the process by opening the Exchange Management Console, and navigating through the console tree to Organization Configuration | Hub Transport. Next, click to the New Send Connector link that's found in the Actions pane. Upon doing so, Exchange will launch the New SMTP Send Connector wizard.
The first thing that you will have to do is to enter a name for the new Send connector. I recommend using something descriptive that conveys that the send connector will be used to send SMTP mail to the Internet.
This screen also contains an option that you can use to specify the intended use for the send connector that you're creating. Since our goal is to be able to send SMTP mail to the outside world, choose the Internet option from the drop down list, as shown in Figure A.
Figure A 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. Since our goal is to send SMTP mail to the Internet, we will use an asterisks in place of an address space. This tells Exchange to send any outbound SMTP mail through this connector (assuming that it isn’t destined for a recipient within the Exchange organization).
To add the address space, click the Add button, and then enter an asterisk into the Address field on the resulting dialog box, as shown in Figure B. Leave the cost at its default value of 1, and click OK.
Figure B Enter an asterisk into the Address field.
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. Unless your ISP requires you to use a smart host, you should use the DNS option.
Click Next, and you will be taken to the screen that is shown in Figure C. As you can see in the figure, 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 on, but you do have the option of specifying a different hub transport server.
Figure C Make sure that the correct hub transport server is listed.
Once you have verified that the correct hub transport server is listed, click Next, followed by New. When you do, your new send connector should be displayed within the Exchange Management Console, as shown in Figure D.
Figure D The new send connector is displayed in the console.
In this article, I have explained that unless your Exchange 2007 organization has an edge transport server and an edge subscription, users will not initially be able to send SMTP mail to the outside world. I then went on to show you how to correct this problem by creating a send connector.
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