SMTP: Configuring the Mail Routing Host Without DNS

The information in this article applies to:

• Microsoft Mail Gateway to SMTP, version 3.0

Mail Routing Host

The Microsoft Mail Gateway to SMTP depends on a mail routing host in the TCP/IP network to route its mail. This is the host defined in the Administrator program under Gateway, SMTP, Setup, in the IP Address of SMTP Router field. The mail routing host is sometimes referred to as the smart host.

The mail routing host routes mail in two ways:

1. Domain name service (DNS)

For details on the DNS, see the application note "Configuring the SMTP Gateway and DNS" (GW0645).

Hosts File Contents

The hosts file is a flat file on the mail routing host that consists of two vital pieces of information: IP addresses and host domain names.

The gateway computer must have an entry in the host file, and so must the domain names assigned to Microsoft Mail postoffices. Domain names are assigned in the Administrator program, under Gateway, SMTP, Address Map, in the SMTP domain field.

For example, the entries in the hosts file for the gateway computer MSMAILGWY.COMPANY.COM at IP address 123.123.4.5 that has Mail postoffice domain names of HQ.COMPANY.COM and SALES.COMPANY.COM, would look like this:

   123.123.4.5   MSMAILGWY.COMPANY.COM
   123.123.4.5   HQ.COMPANY.COM
   123.123.4.5   SALES.COMPANY.COM