hi, Wed, Oct 10, 2018 at 08:55:36, vas wrote about "Re: [Exim-users] домен mpeks.tomsk.su":
> Вопрос к знатокам почтовых протоколов. Невозможность разрезолвить > домен получателя - это временная ошибка или постоянная с точки зрения > доставки почты? The lookup first attempts to locate an MX record associated with the name. If a CNAME record is found, the resulting name is processed as if it were the initial name. If a non-existent domain error is returned, this situation MUST be reported as an error. If a -> temporary error is returned, the message MUST be queued and retried later (see Section 4.5.4.1). If an empty list of MXs is returned, the address is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host. If MX records are present, but none of them are usable, or the implicit MX is unusable, this situation MUST be reported as an error. (RFC5321 строка 3860, стрелка от меня) Прямого указания, что SERVFAIL (Server failure, RCODE == 2 в терминах RFC1035) не увидел, но зато там же есть такое: Resolvers are responsible for dealing with the distribution of the domain space and dealing with the effects of name server failure by consulting redundant databases in other servers. А в RFC1034 целая глава: 5.2.3. Temporary failures In a less than perfect world, all resolvers will occasionally be unable to resolve a particular request. This condition can be caused by a resolver which becomes separated from the rest of the network due to a link failure or gateway problem, or less often by coincident failure or unavailability of all servers for a particular domain. It is essential that this sort of condition should not be signalled as a name or data not present error to applications. This sort of behavior is annoying to humans, and can wreak havoc when mail systems use the DNS. While in some cases it is possible to deal with such a temporary problem by blocking the request indefinitely, this is usually not a good choice, particularly when the client is a server process that could move on to other tasks. The recommended solution is to always have temporary failure as one of the possible results of a resolver function, even though this may make emulation of existing HOSTS.TXT functions more difficult. Думаю, можно на это ссылаться. > А вообще история мутная. Делегирование tomsk.su прекращалось на > несколько часов 2 октября, Recent Bounces показываются за 4-6 октября, > автор groups.io говорит "their DNS records had was fixed > around 11pm pacific time Friday night. That's when we started to be > able to send email to them again" (это видимо пятница 5 октября). Где-то эти SERVFAIL задержались на несколько дней? Я бы не удивился. -netch- _______________________________________________ Exim-users mailing list Exim-users@mailground.net http://mailground.net/mailman/listinfo/exim-users
