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:	Default value of unknown_address_reject_code
Group:	Postfix-users
From:	Peter Rabbitson
Date:	15 Apr 2007

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?

Thanks

Peter