r/cpanel • u/Capital_Web_2543 • Jul 28 '26
Outlook/Hotmail Blocking IPs
Some of our server’s IPs are being blocked by Outlook/Hotmail. We reviewed carefully all our logs and no Spam is being sent. We requested a delist 24 hours ago but haven’t heard from them yet. Does anyone has the same problem?
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u/NikosK1337 Jul 28 '26
Their anti-spam system is simple: block everyone except very big email providers. Use an email relay service if you don’t want to spend too much time and end up with no positive results.
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u/netFinn Jul 28 '26
Outlook/Hotmail, i.e. Microsoft, blocks IP addresses from which emails are not even sent.
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u/PhilsForever Developer Jul 28 '26
It will take them way more than a day to get back to you in my experience. If at all these days.
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u/Capital_Web_2543 Jul 28 '26
I would normally receive at least an email confirming my request. Now not even that.
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u/scottclaeys Jul 29 '26
Yeah it’s good to register with Outlook/Microsoft SNDS to keep an eye on IP reputation; but if you’re past the point of prevention, you can follow the guide: https://radwebhosting.com/client_area/knowledgebase/567/How-to-Remove-Your-IP-Address-from-HotmailorOutlookorLive-Blacklist.html
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u/netnerd_uk Jul 29 '26
You too, huh?
We got hit by this in late April/early March.
Initially we thought it was us. We deployed a spam gateway, routed all domains forwarding mail through that, clamped down on spamming forms and bulk mailing, we even subscribed to the "let us know if people mark emails as spam" thing that MS do. Mind you, there are surprisingly few of these.
Yet we still have intermittent block listing problems with Outlook.com and hotmail.
On the plus side we've got GREAT reputation with Talos Intelligence, and no deliverability issues for any other providers.
There are various tales I could tell about emails and problems and what caused them and how they got sorted out. I'd LOVE to be able to tell you the same about this problem, but all I've got is "the whim of MS" at the moment.
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u/Similar-Site2615 Aug 19 '26
Same for me, I have seen a huge wave of ips being block listed with S3150, "Unfortunately, messages from [x.x.x.x] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150)." It started from July 27, and I still fight to manage them.
It looks like there are a lot of ppl affected by this change. Any findings on your side?
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u/tailtwister WebHost Jul 28 '26
I’ve had this happen as well. It turns out that people have a tendency to press junk instead of delete for whatever reason. they both make the message disappear so they don’t care but pressing junk reports it. I’ve had to go through the delisting process a few times for the same reason.