On 9 Jan 2004 at 9:18, Harald Tveit Alvestrand
<harald(_at_)alvestrand(_dot_)no> spoke, thus:
Why doesn't your friend use ETRN to trigger delivery of his queued mail
from his mate whenever he gets online?
He doesn't want his mate getting his mail while he's not available if he
will be available shortly after. The idea is to restrain clients from
passing onto the next MX, and thereby let his mail fall into his own
responsibility when the unavailability of his host is either known to be
temporary or is simply not long enough to justify any resulting policy
differences between hosts. His mate could, if this were a dynamic DNS
provider, be half-way across the world when the client only needed to wait
a few minutes before it could deliver to the final destination. This is
just an example. Also, etrn/similar don't solve the RBL problem.
That way, the 4-hour delay is avoided without requiring global changes to
the Internet infrastructure....
The unilateral thought of all of us, no doubt. :-) It is quite outrageous
as far as requirements go for such a simple feature, but I honestly can't
see a simple way otherwise that doesn't involve inter-host communication
which, obviously, can't happen if the backed-up host is out, or other
scheduled checking. If his mate could somehow know that he (my friend)
were down, his mate could serve him, and when he returned his mate could,
upon instruction by him, give an appropriate number and message to the
effect that the primary was up, go and deliver to him, when all clients
tried sending to my friend through his mate. Would implementation of such
a system be worthwhile, even if it meant periodic checks by his mate that
my friend was down? The MX concept is very good, but very heavy-handed
and served a time long ago when it really was necessary. Also, the demand
on the speed of mail delivery has gone up with the number of email users
on the net and their expectations of it. In terms of saved bandwidth,
there's a slight argument for the cost of a DNS query. I would be willing
to implement it either way, though preferably the least destructive one.
Cheers,
Sabahattin
--
Thought for the day:
Dictatorship (n): a form of government under which everything
which is not prohibited is compulsory.
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