SMTP Domains

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1

Domains in the SMTP service are different from DNS domains and Windows domains. The SMTP service domains are used for organizing messages for delivery.

The Simple Mail Transfer Protocol (SMTP) virtual server has at least one domain--the default local domain. You can add more domains and configure them to be local or remote. You can delete any domain except the default domain.

Local Domains

A local domain is a DNS domain that is serviced by the local SMTP server. Any message with a local domain name that arrives at an SMTP server must be delivered locally to a Drop directory or returned to the sender with a non-delivery report (NDR). Local domains are sometimes referred to as service domains or supported domains. E-mail addresses with local domain names are often referred to as local addresses.

If the domain is local, you can designate it as default or alias. There is one default domain. It is used to stamp message headers that lack a domain specification. An alias domain is an alias of the default domain. If you add a domain and assign it as the new default, the previous default changes to an alias domain.

Remote Domains

Domains that are not local are known as remote or nonlocal domains, and e-mail addresses with remote domain names are referred to as nonlocal addresses. The SMTP service looks up remote domains in DNS.

If you want to set unique delivery requirements for a specific remote domain, you can add a remote domain and configure it accordingly. For example, you can add a remote domain and require that the SMTP service always use Transport Layer Security (TLS) encryption in sessions with that domain. Or, you can change the routing so that messages sent to one remote domain are routed to another remote domain. Use the Domain Properties dialog box to configure domains.

This section includes the following information: