Postfix : warning: inet_protocols: IPv6 support is disabled

Issue:

: warning: inet_protocols: configuring for IPv4 support only
: fatal: config variable inet_interfaces: host not found: localhost
: warning: inet_protocols: IPv6 support is disabled: Address family not supported by protocol
: warning: inet_protocols: configuring for IPv4 support only

Solution:

# /usr/sbin/postconf | grep inet_protocols
inet_protocols = all


# vi /etc/postfix/main.cf

Search for: inet_protocols and change it from “inet_protocols = all” to “inet_protocols = ipv4”

Save /etc/postfix/main.cf and and restart Postfix service:
# /etc/init.d/postfix restart