On Sun, Sep 24, 2023 at 06:25:36PM -0400, Wietse Venema via Postfix-users <postfix-users@postfix.org> wrote:
> Wietse Venema via Postfix-users: > > It's a rather long explanation for "why not do X". like several > > times longer than the text that explains what protocol preferences > > do. And this is the only place where adding that text would help. > > I updated the text a little: > > Notes for mail delivery between sites that have both IPv4 and IPv6 > connectivity: > > * The setting "smtp_address_preference = ipv6" is unsafe. All > deliveries will suffer delays when IPv6 is not available even > while the destination is still reachable over IPv4. Mail may > be stuck in the queue with Postfix versions < 3.3 that do > not implement "smtp_balance_inet_protocols". For similar reasons, > the setting "smtp_address_preference = ipv4" is also unsafe. > > * The setting "smtp_address_preference = any" is safe. With this, > and "smtp_balance_inet_protocols = yes" (the default), only > half of deliveries will suffer delays if there is an outage > that affects IPv6 or IPv4, as long as it does not affect both. > > I added smtp_balance_inet_protocols to the discussion, because it > mitigates the safety issue somewhat, perhaps to the point that some > people with low email volume are willing to suffer the delays. > > Wietse > _______________________________________________ > Postfix-users mailing list -- postfix-users@postfix.org > To unsubscribe send an email to postfix-users-le...@postfix.org Sadly, I need smtp_address_preference = ipv4 because some reputation systems (spamhaus, I think) don't realise that an entity might only have a single ipv6 address. They seem to think that everyone has at least 64 addresses. So, when an unrelated tenant near my VPS sent spam from their ipv6 address, it tainted my ipv6 address's reputation. cheers, raf _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
