I'm trying to change the source IP of my mailing server from IPv6 to IPv4.
I'm running Debian 6.0.7 with Postfix 2.7.1 mail service and ISPConfig 18.104.22.168.
I found lots of forums saying that is easy as change the parameter
smtp_address_preference = any to
smtp_address_preference = ipv4 in
/etc/postfix/main.cf config file, but I can't find this parameter in that file, and if I run
postconf smtp_address_preference command it prompts
smtp_address_preference: unknown parameter.
I tried adding it and reloading the service with no luck... Can anyone tell me what I'm doing bad?