Technical data

Configuring and Managing SMTP
17.1 Key Concepts
17.1.5.2 Using SMTP Zones and Alternate Gateways
When configuring SMTP, you supply the name of the domain for your
environment with the /ZONE qualifier to the SET CONFIGURATION SMTP
command. If you do not supply a domain name, the zone defaults to one level
higher than your local domain. For example, if the fully qualified domain name is
a.b.com , the default value of /ZONE is b.com (assuming that, because TCPIP has
been started, the domain is known).
Mail for delivery outside of your zone is sent to its destination by the alternate
gateway, as defined by the /GATEWAY qualifier. If you define an alternate
gateway, SMTP routes mail to destinations outside the SMTP zone defined on the
alternate gateway. SMTP uses MX records for routing mail within the zone and,
if no alternate gateway is defined, elsewhere as well.
The following example defines the alternative gateway MY.ALT.MYZONE.COM
and the zone MYZONE.COM.
TCPIP> SET CONFIGURATION SMTP/GATEWAY=ALTERNATE=MY.ALT.MYZONE.COM
TCPIP> SET CONFIGURATION SMTP/ZONE=MYZONE.COM
See the Compaq TCP/IP Services for OpenVMS Management Command Reference
manual for a detailed desciption of the SET CONFIGURATION SMTP command.
To send mail to the alternate gateway, SMTP does an MX lookup on the alternate
gateway and uses the resulting list of MX records to get the mail to the alternate
gateway. To understand the advantages of this method over a simple lookup of A
records, consider the following example.
The alternate gateway and zone are configured as follows:
TCPIP> SHOW CONFIGURATION SMTP
...
Alternate gateway: relay.abc.com
...
Zone: abc.com
...
Further, there is no A record configured for the destination domain
relay.abc.com. Therefore, relay.abc.com is not a valid host name. This is
demonstrated by the following command:
TCPIP> SHOW HOST RELAY.ABC.COM
%TCPIP-W-NORECORD, Information not found
-RMS-E-RNF, record not found
There is no such host as relay.abc.com because relay.abc.com is only an MX
destination domain with multiple records at the same preference.
MX records have been set up accordingly. For example:
TCPIP> SHOW MX RELAY.ABC.COM
BIND MX database
Server: 1.2.3.4 host.abc.com
Gate address Preference Gate name
1.3.4.5 100 mail11.abc.com
1.3.5.6 100 mail13.abc.com
2.4.5.6 200 mail2.abc.com
2.4.5.7 200 mail1.abc.com
3.4.5.6 300 mail21.abc.com
3.4.6.7 300 mail12.abc.com
Configuring and Managing SMTP 17–5