Microsoft is updating the SNDS and mentions that "SNDS will move to a
new, more secure URL". As part of that, other links/URLs are apparently
changing as well, which is causing some brokenness.
As for the S3150 error, that means you have hit the limit allowed for
your IP. If you stop sending to OLC accounts, you can start up again in
a few days and the error will be gone (until you hit the limit again).
Alternatively, you can fill out their support form and get the standard
denial, and then escalate that, and their team will almost always
mitigate the IP manually, and sometimes even increase the limits.
Our experience of that:
https://docs.hetzner.com/robot/dedicated-server/troubleshooting/microsoft-blacklist#olc-outlook-consumer
For the past few years Microsoft has been moving away from S3140 (total
IP/subnet block) and towards S3150 (throttle of IP based on individual
limits).
Kind regards
Bastiaan van den Berg
Am 30.12.2025 um 01:38 schrieb Graeme Fowler (Admin) via mailop:
It finally happened! The mailop list server has been blocked by Microsoft,
resulting in a slew of suspended subscriptions.
The problem I have is that I simply can't reach the link they provide in the
error message:
*Diagnostic-Code*: smtp; 550 5.7.1 Unfortunately, messages from
[91.132.147.157] weren't sent. Please contact your Internet service provider
since part of their network is on our block list (S3150). You can also refer
your provider to http://mail.live.com/mail/troubleshooting.aspx#errors.
[Name=Protocol Filter Agent][AGT=PFA][MxId=11BC88DCCD3A3675]
[BN3PEPF0000B06E.namprd21.prod.outlook.com 2025-12-29T08:43:13.886Z
08DE446E687E5366]
The link redirects 3 or 4 times to a page which gives a 500 internal server
error. This happens regardless of browser, OS, whether logged in to an MS
account or using private/incognito mode.
In the absence of any other capability to address this with MS by following
their directions, subscribers using live/outlook/Hotmail addresses should
consider their subscriptions at risk.
Graeme
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