On sam. 11 janv. 15:44:24 2020, thomas brenac wrote:
> j'ai deux serveur mail, un IPv4 et l'autre IPv6. Question idiote: pour les
> enregistrement DNS mettriez vous les deux avec la meme priorite ?
Oui. Les clients smtp sont assez intelligents pour essayer un mix des deux.
Voir le manuel postfix (man 5 postconf), mais ne pas regarder le IPV6_README,
il est complétement dépassé :
smtp_address_preference (default: any)
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. This feature has no effect unless the inet_proto‐
cols setting enables both IPv4 and IPv6.
Postfix SMTP client address preference has evolved. With Postfix 2.8
the default is "ipv6"; earlier implementations are hard-coded to prefer
IPv6 over IPv4.
Notes for mail delivery between sites that have both IPv4 and IPv6 con‐
nectivity:
• The setting "smtp_address_preference = ipv6" is unsafe. It can
fail to deliver mail when there is an outage that affects IPv6,
while the destination is still reachable over IPv4.
• The setting "smtp_address_preference = any" is safe. With this,
mail will eventually be delivered even if there is an outage
that affects IPv6 or IPv4, as long as it does not affect both.
This feature is available in Postfix 2.8 and later.
smtp_balance_inet_protocols (default: yes)
When a remote destination resolves to a combination of IPv4 and IPv6
addresses, ensure that the Postfix SMTP client can try both address
types before it runs into the smtp_mx_address_limit.
This avoids an interoperability problem when a destination resolves to
primarily IPv6 addresses, the smtp_address_limit feature eliminates
most or all IPv4 addresses, and the destination is not reachable over
IPv6.
This feature is available in Postfix 3.3 and later.
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