Postfix inet_interfaces, which are local network interface addresses to receive mail on the Postfix mail system. With our Server Management Services, Bobcares offers solutions to your server-related problems.

Postfix inet_interfaces

inet_interfaces is a Postfix setup parameter that tells the local network interface addresses to receive mail on the mail system. By default, the value will be “all” for the parameter. This default value will enable receiving mail on all network interfaces. The parameter becomes “loopback-only” to receive mail on loopback network interfaces only.

The option also governs email delivery to user@[ip.address]. The IP will be within []. Also, we need to restart Postfix when modifying this parameter. When inet_interfaces specifies only one non-loopback IPv4 and/or IPv6 address, the Postfix SMTP client will use this address as the IP source address for outgoing mail.

It can stop each Postfix instance from reaching external SMTP servers on the “other side” of the firewall on a multi-homed firewall with distinct Postfix instances listening on the “inside” and “outside” interfaces. Setting smtp_bind_address to 0.0.0.0 removes the risk of an IPv4 difficulty while setting smtp_bind_address6 to:: eliminates the possibility of an IPv6 problem.

For multi-homed firewalls, it is better to avoid inet_interfaces at default. Instead, use explicit Ip addresses in the master.cf SMTP server configurations. This preserves the Postfix SMTP client’s loop detection by ensuring that both sides of the firewall are aware that the other IP address still belongs to the same host. Setting $inet_interfaces to a single IPv4 and/or IPV6 address is especially useful with secondary IP address virtual hosting when each IP address serves a separate domain (and has a different $myhostname setting).

Let’s look at the proxy interfaces parameter, which is used to specify network addresses that are sent to Postfix via a proxy or address translator.

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Conclusion

In the configuration parameter, Postfix inet_interfaces having somewhat varied settings, we can modify the master.cf file and bind port 25 to numerous IP addresses.