Re: Default value of unknown_address_reject_code

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Default value of unknown_address_reject_code
\ Peter Rabbitson (15 Apr 2007)
. \ Sandy Drobic (15 Apr 2007)
. . \ Peter Rabbitson (16 Apr 2007)
. . . \ Noel Jones (16 Apr 2007)
. . . . \ mouss (16 Apr 2007)

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Subject:	Re: Default value of unknown_address_reject_code
Group:	Postfix-users
From:	mouss
Date:	16 Apr 2007

Noel Jones wrote:
> At 05:19 AM 4/16/2007, Peter Rabbitson wrote:
>> Sandy Drobic wrote:
>>> Peter Rabbitson wrote:
>>>> Hi,
>>>>
>>>> I have some trouble understanding why the default for
>>>> unknown_address_reject_code is 450. Here is my reasoning:
>>>>
>>>> Assume that we specified *reject_unknown_recipient_domain* as one
>>>> of the
>>>> *smtpd_recipient_restrictions*. If we leave
>>>> *unknown_address_reject_code* at its default 450, mail to
>>>> non-existing/non-resolvable domains will be retried until
>>>> *maximal_queue_lifetime* is reached. However the _same_ will happen if
>>>> we do not add *reject_unknown_recipient_domain* to
>>>> *smtpd_recipient_restrictions* to begin with. Naturally comes the
>>>> question - what is *reject_unknown_recipient_domain* good for
>>>> without a
>>>> 5xx response code?
>>> It's the same as with "reject_unlisted_recipient". You can specify
>>> exactly
>>> when and to what clients the restriction is applied. The default is to
>>> apply it at the end of smtpd_recipient_restrictions, but you
>>> probably want
>>> to place it before greylisting or RBL checks.
>>
>>
>> I am afraid I don't understand your answer. What do you mean by
>> "specify exactly when and to what clients the restriction is
>> applied", and how is it relevant to the _effect_ of the restriction
>> (4xx or 5xx).
>>
>> Peter
>
> In response to your original question, postfix defauts to 4xx reject
> codes so that mail will not be lost in case of accidents. You change
> it to a 5xx code when you're ready.
>

to give OP an example: if you just install postfix and a dns server, and
misconfigure the latter, mail would bounce. with a 4xx, you have the
time to fix the dns and postfix servers.