On Thu, Dec 05, 2024 at 06:20:11AM -0800, Michael Peddemors via mailop wrote:
> And for the record, ESP's and senders should NEVER assume that they can send
> even 100 recipients.
Well, senders really SHOULD be able to, the fact that some large
providers feel at liberty to violate the specification, and the communit
lets them get away with it is regrettable... Postfix defaults to at
most 50 recipients per SMTP envelope of a multi-recipient message.
> And PIPELINING should go the way of the DODO..
I strongly disagree. Correctly implemented ESMTP PIPELINING is good for
both senders and recipients by significantly reducing the latency of
message deliveries, freeing up server resources to handle other traffic.
> Senders should carefully watch for the response code on every RCPT TO,
> and IF you are an ESP that gets a 452, stop trying to send to more
> RCPTS in the same session.
Sure, once a 452 is seen, defer the remaining recipients.
> (Even though MagicMail doesn't advertise PIPELINING, amazing how many
> try to PIPELINE anyways.)
That's no ESMTP PIPELINING, that's attempted botnet abuse, perhaps
also a few half-baked MTAs, by someone who barely glanced at the spec,
but those would not be the majority of such traffic.
Postfix, Exim, ... implement correct PIPELINING, and don't engage it
when not advertised by the receiving system. If your system chooses
to spend more time connected to each client, your call I guess, but
not a choice I'd make.
--
Viktor.
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