Why is smtp_address_preference not used?

[ñull]

In LC mail server setting I see the select box outbound IPv6 address. One of the options is no outbound IPv6 I would expect that then smtp_address_preference = ipv4 is added to /etc/postfix/main.cf but I cannot find it there. I believe my mails are marked spam because recently ipv6 was activated on my vServer and may be postfix is using IPv6 now.

See also http://serverfault.com/questions/565...-and-when-ipv4

[ñull]

Effectively. I manually added smtp_address_preference = ipv4 and from then on emails arrived normally like before.

[antondollmaier]

I believe my mails are marked spam

Please check your logfiles on the exact reasons.

because recently ipv6 was activated on my vServer and may be postfix is using IPv6 now.

then please configure proper Reverse- and Forward DNS for your new IPv6 address.

It's 2016 - get your IPv6 setup working. More and more ISPs (even T-Mobile Germany!) support and deploy IPv6 for the end users.

See also http://serverfault.com/questions/565...-and-when-ipv4

Inet_protocols should be the desired setting for this: it also controls the inbound mail sockets:

http://www.postfix.org/postconf.5.html#inet_protocols

[ñull]

inet_protocols configuration is in fact correctly used by LC and I oversaw that. Except for SPF (DNS still propagating) all seems ready after I followed your suggestion. Already delivered to Gmail via IPv6. Thanks for your encouragement!

[antondollmaier]

Except for SPF (DNS still propagating) all seems ready after I followed your suggestion. Already delivered to Gmail via IPv6. Thanks for your encouragement!

Thank you for another IPv6 deployment

In general: IPv6 behaves like IPv4. It's basically another IP you have to take care of.

As it's also a different protocol stack, some tools (iptables!) have to be considered for IPv6 as well. Apart from that, the same rules apply for IPv6 mail traffic as for IPv4 mail traffic.