J C Lawrence <claw(_at_)kanga(_dot_)nu> schrieb/wrote:
On Sun, 6 Apr 2003 18:19:26 -0400
waltdnes <waltdnes(_at_)waltdnes(_dot_)org> wrote:
Then fer-cryin-out-loud, hold off on the "OK" response for a few
seconds and wait till the email is accepted. If it isn't, issue the
appropriate 5xx code after DATA:.
And when the message turns out to be addressed to an alias or forward
which points outside that MX'es domain?
There's no reason why it could not work in this situation: You hold off
the "OK" until you know that the message has been delivered, delivery
has failed /or/ a timeout has been elasped.
Or the system that handles mail spooling (final delivery) is not the
same as the recipient MX (almost always the case for corporates), and
reponse time from the spool machine may exceed an hour (seen this
quite commonly during mail bursts)?
In this case you could configure your system to temporarily reject mail
from outside until the spool machine responds timely again.
Consider AOL's case for starters. From what I can tell they have a
three-level setup, with a first line of simple receivers, a middle area
of message routers and analysers (eg where the silent discards happen),
and then a set of back end storage servers handling the LDA business.
Even this system should not receive mail faster than the analysers can
handle it and storage servers can tuck it away. Each level can start to
temporarily reject messages (or connection) until the next level can
handle the mail.
Claus
--
http://www.faerber.muc.de/
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