On Oct 31, 2011, at 9:14 AM, Tony Finch wrote:
Steve Atkins <steve(_at_)blighty(_dot_)com> wrote:
Each delivery attempt consumes significant system resources, both at the
client and the server.
Maybe ten or twenty years ago.
Yahoo! is currently handling somewhat over 300,000 delivery attempts a
second[1]. You don't need to increase the average cost of a mail delivery
(either by increasing the cost of a delivery attempt or by increasing
the number of delivery attempts per message) by much for it to add
up to significant costs.
If, for example, the client was continually deferred and retried every
minute,
That would be silly. (Still, some of my users run Exchange servers that do
this.)
It's what you seemed to be suggesting as a way for poorly behaved
clients to deliver mail in a timely manner in the face of 4xx deferrals.
And it is something that some badly behaved clients do do - even when
they have thousands of messages queued for a specific server.
Cheers,
Steve
[1] http://visualize.yahoo.com/