After the Postfix server has been installed you can adjust the configuration files /etc/postfix/master.cf and /etc/postfix/main.cf.
Generally the Postfix server is ready to operate even without any modification to the configuration files as the installation program attempts to determine system-specific parameters, such as the system’s domain name, automatically via system calls and by inspecting the DNS Resolver’s configuration file /etc/resolv.conf and to save these parameters in the configuration file main.cf. You should therefore store the system’s domain name (e.g. systemx.mycompany.com) and any DNS aliases on the DNS server concerned before performing installation. To do this, you must configure the /etc/resolv.conf file accordingly (see the section “Configuring the DNS resolver”).
If it was possible to perform automatic Postfix configuration successfully, the Postfix server is started automatically depending on the answer to the installation query AutoStartPostfix after installation has been completed.
In the standard configuration the Postfix server operates merely as a mail end system, but not as a mail relay. If the Postfix server is also to be used as a mail relay, you must adapt the Postfix configuration file /etc/postfix/main.cf accordingly. More detailed information on this can be found in the man pages on the Postfix server and in the documentation on the topic of Postfix which is referred to in “Related publications”.
CAUTION!
Proceed particularly carefully when you configure the Postfix server as a mail relay because a mail relay which can be accessed openly from the Internet very quickly attracts mail spammers. Among other things, this can result in your Internet access being blocked by the Internet service provider.