smtp_address_preference

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smtp_address_preference

Luigi Rosa-2
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The documentation says

"The address type ("ipv6", "ipv4" or "any") that the Postfix SMTP client will
try first, when a destination has IPv6 and IPv4 addresses with equal MX
preference."

What exacly happens if example.com has

example.com. IN MX 10 mail.example.com.
mail.example.com. IN A 1.2.3.4
mail.example.com. IN AAAA 2001:1234:abcd::beef

and

smtp_address_preference = any


What protocol is tried first with "any" setting?



Ciao,
luigi

- --
/
+--[Luigi Rosa]--
\

East, West, just points of the compass, each as stupid as the other.
    --Dr. No, "007 Dr. No"
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Re: smtp_address_preference

Wietse Venema
Luigi Rosa:

> The documentation says
>
> "The address type ("ipv6", "ipv4" or "any") that the Postfix SMTP client will
> try first, when a destination has IPv6 and IPv4 addresses with equal MX
> preference."
>
> What exacly happens if example.com has
>
> example.com. IN MX 10 mail.example.com.
> mail.example.com. IN A 1.2.3.4
> mail.example.com. IN AAAA 2001:1234:abcd::beef
>
> and
>
> smtp_address_preference = any
>
>
> What protocol is tried first with "any" setting?

Oh ye of little faith. The answer is: any.  Postfix makes a random
choice.

This is the safest choice, because it prevents mail from getting
stuck when IPv4 or IPv6 is unavailable, as long as one of them
works.

        Wietse