HOW TO: Configure a Remote Domain for an IIS 5.0 SMTP Mail Relay Server in Windows 2000

This article describes how to configure a remote domain for an Internet Information Services (IIS) 5.0 Simple Mail Transport Protocol (SMTP) mail relay server.

IIS 5.0 in Windows 2000 includes a full-featured SMTP server that you can use to route mail on your internal network. The SMTP server can also accept mail from the Internet. Although the IIS 5.0 SMTP service does not include an easily accessible mechanism to retrieve mail, it can play a vital role in accepting mail from the Internet and relaying it to your SMTP/POP3 server (such as Microsoft Exchange 2000 Server). You can configure the IIS 5.0 SMTP server to accept mail for the domain to which the computer belongs, as well as for other domains.

A standalone server that is running the IIS 5.0 SMTP service provides a good measure of security because it acts as a layer of separation between the corporate mail server and inbound connections from the Internet. A standalone Windows 2000-based server isolates the server from the Active Directory security boundaries of the internal network. You can configure the standalone SMTP server to use the corporate mail server as a smart host. You can then configure the standalone IIS 5.0 SMTP server to relay mail that is directed only to the remote domain. If you do this, all other mail is not relayed and is rejected.

How to Configure a Standalone IIS SMTP Server to Relay to a Remote Domain

1. On the Administrative Tools menu, click Internet Services Manager.
2. Expand your server, and then expand Default SMTP Virtual Server in the left pane of the Internet Information Services console.
3. Right-click the Domains node, point to New, and then click Domain.
4. Click Remote, and then click Next.
5. In the Name box, type the name of the mail domain. You can use a single domain, or you can use an asterisk (*) as a wildcard entry (the asterisk must be at the beginning of the name and be separated from the rest of the name by a period). For example, if you want the remote domain to accept mail for other-domain.com and all its subdomains, use the name *.other-domain.com. Click Finish.
6. Right-click the remote domain you just created, and then click Properties.
7. Select the Allow incoming mail to be relayed to this domain check box to allow the SMTP server to act as a mail relay.
8. Click Forward all mail to smart host, and then type the IP address or host name of the internal network's corporate mail server. If you use an IP address, make sure to surround the IP address with brackets. For example, [nnn.nnnn.n.n].
9. Click OK.
10. Right-click the Default SMTP Virtual Server node, and then click Stop. After the server has stopped, right-click the node, and then click Start.

Troubleshooting

After you configure the remote domain, all mail that is addressed to the remote domain name is relayed to the smart host that you configured. Mail that is not deliverable is stored in the Inetpub\Mailroot\Badmail folder.