Asking them why, can't be answered. The real problem here is that they
don't know why anyone was blocked either.
As was stated the code has been worked on over the years by many
individuals that no longer work in that department. New code was added
most likely, that when implemented caused the issue.
The complaints to them were just typical noise because it happens all
the time. It happens so often that majority here know that you open a
ticket, get an email that states you aren't being blocked, you reply
that you are with your ip's, you get a response that they've modified
your rate limit, all of a sudden you aren't blocked anymore. Rinse and
Repeat. They might as well make it easier by automating the message that
you aren't being blocked when the block is put in place. We have our
IP's registered with SNDS so they know who we are already.
David
--
https://dprall.net
On 2/26/2026 1:49 PM, Matthew Pounsett via mailop wrote:
On Wed, Feb 25, 2026 at 9:33 PM postfix--- via mailop <[email protected]
<mailto:[email protected]>> wrote:
Sorry to read of your woes, but I am happy that one of the oligopolists
is shaking the tree and causing pain to the whole industry. Because it
is time for the industry to stop the growing VOLUME of emails and focus
on QUALITY. Less is more, despite technology's advancement that makes
more verbal diarrhea (LLMs) and feed it to the same limited number of
human recipients at higher frequency. ACCEPT THAT YOUR MARKET HAS
GROWN
BEYOND USEFUL SIZE AND NEED A HEALTHY SHRINKING.
You seem to assume that everyone sending email to recipients on
outlook is sending marketing email. There are lots of us who send
email for entirely non-commercial reasons, and others who are sending
commercial but non-advertising email. And then there are people's ISPs,
who aren't originating any email at all, simply delivering mail from
their users to Microsoft's users.
As far as I can tell, Microsoft does not distinguish between any
senders, regardless of the type of email.
In my case (I started the thread that got killed on the weekend), I host
an ~1800 subscriber technical mailing list, similar in function to this
list, that averages single-digit emails per day, and has under 200
subscribers with their mail on outlook.com <http://outlook.com> MX
servers. Outlook randomly started blocking mail from that list to
recipients using outlook.com <http://outlook.com> mail servers, along
with transactional email from our self-help portal and the chat server
we run (people trying to do password recoveries, or signups), and human-
sender email from our staff to individuals with outlook mailboxes.
Email from us to Outlook isn't high volume. I imagine by the
standards of most of this lists's subscribers we barely register as a
rouding error.
To be absoolutely clear, as far as I can tell we have never received a
response from an outlook.com <http://outlook.com> mail server indicating
we're being rate limited.
And yet, we were blocked. And when I heard from Outlook's mail support,
they simultaneously claimed:
- they couldn't find any indication that our IP address was blocked
- the block on our IP address has been mitigated (these seem mutually
exclusive, but maybe I'm missing nuance)
- and "I am unable to provide any details about this situation since we
do not have the liberty to discuss the nature of the block" (a direct
quote on the subject of the definition of the S3150 error).
So they won't or can't admit we were blocked (but they're also willing
to unblock us as long as we ask!), and they're outright refusing to tell
us what caused the block, so we have no way of knowing how to avoid
being blocked in the future. This isn't "shaking things up"... this is
being actively hostile to legitimate senders.
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