On 2026-02-20 17:01, Michael Wise via mailop wrote:
It’s throttling.
Slow down your deliveries.
S3150 is what you get when you don't slow down after seeing 4xx. 😊
(I've just now (well, reading all the recent messages) seen Michael has
a Microsoft email address).
Assuming this information is100% accurate, how exactly is this advice
supposed to be acted upon in a practical manner?
The advice to slow down delivery seems only appropriate to a bulk email
sender, especially for companies who send out hundreds of thousands or
millions of emails for a campaign. A campaigner's job is to get those
queued mails delivered as fast as possible and their systems are going
to be tailed for this specific job, so they *might* actually be watching
for 4xx messages to tune their delivery rate.
For *everybody else on the planet*, this is an unreasonable expectation.
Slow down? This isn't a fixed-size delivery, this is a bucket that never
empties.
In our case the email we are sending out is *transactional*; signups,
password resets, activity notifications. We're fielding daily complaints
from people trying to sign up for for sites that we host and not
receiving confirmation emails.
The frustration I experience myself and see in others is no doubt borne
out of Microsoft's unwillingness to engage or act in a way that is, from
an outside view, sensible and reasonable. We're also left holding the
bag when people complain, because if Microsoft blocks our IPs its
obviously our fault, right?
I refuse to accept that, nor should others.
Michael
--
Michael Brown
Civilized Discourse Construction Kit, Inc.
https://www.discourse.org/
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