On 24/02/2026 16:13, Paul Smith* via mailop wrote:
On 24/02/2026 12:45, Gellner, Oliver via mailop wrote:
We receive the same error messages for all servers since 2026-02-23
18:45 UTC. It's unlikely that Microsoft suddenly received spam from
all IP addresses of all kind of unrelated organizations yesterday
evening. Probably some algorithm went nuts there.
I thought we were being *rate limited*, but we're not, nothing at all
is going out to outlook.com, hotmail.com, etc. Mail to business M365
is going out fine.
But, bizarrely, we have one host on the same /29 range which we've set
up to send out all the 'slightly dodgy' stuff - the email that people
forward from their business email to personal gmail/outlook.com etc
(despite us telling them not to), so it may contain spam, and fail
DMARC, etc. I've just looked, and that's sending mail fine to
Outlook.com/hotmail.com/etc. That's the first one I'd have thought would
be an issue. All the ones with 'good quality' emails are being blocked,
and the 'slightly dodgy' emails are being let through.
As it's the same /29 range as our other servers, that would suggest it's
not a 'bad neighbour' problem.
I may be tempted to route our 'good' stuff through our 'dodgy' server...
Paul
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