Все о MDaemon (#3) - [57] :: В помощь системному администратору

Asusnovo RFC 2821, секция 4.2.1 Reply Code Severities and Theory.
Цитирую:
4yz Transient Negative Completion reply
The command was not accepted, and the requested action did not
occur. However, the error condition is temporary and the action
may be requested again. The sender should return to the beginning
of the command sequence (if any). It is difficult to assign a
meaning to "transient" when two different sites (receiver- and
sender-SMTP agents) must agree on the interpretation. Each reply
in this category might have a different time value, but the SMTP
client is encouraged to try again. A rule of thumb to determine
whether a reply fits into the 4yz or the 5yz category (see below)
is that replies are 4yz if they can be successful if repeated
without any change in command form or in properties of the sender
or receiver (that is, the command is repeated identically and the
receiver does not put up a new implementation.)

RFC 2821 секция 4.5.4.1 Sending Strategy
цитирую:

The general model for an SMTP client is one or more processes that
periodically attempt to transmit outgoing mail. In a typical system,
the program that composes a message has some method for requesting
immediate attention for a new piece of outgoing mail, while mail that
cannot be transmitted immediately MUST be queued and periodically
retried by the sender. A mail queue entry will include not only the
message itself but also the envelope information.

Короче на любой ответ с кодом 4xx МТА должен повторять посылку писем. Если МТА этого не делает и нарушает RFC - этого его проблемы и плевать нужно на такие МТА! Для критичной почты занеси ip или домены (ip предпочтительнее) в White List грейлистинга.

P.S. Есть такие МТА, которые до сих пор юзают устаревшмй метод борьбы со спамом: встречную проверку ( на существование адреса отправителя.(Sender verification with callback) В таких случаях само собой почта от них никогда не придет. Поможет только White List.

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В сортире лучше быть юзером, чем админом...

Модерирует : lynx, Crash_Master, dg, emx, ShriEkeR
emx (17-01-2009 20:15): http://forum.ru-board.com/topic.cgi?forum=8&topic=30717	Версия для печати • Подписаться • Добавить в закладки
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