As Michael says, it might be a larger block that just your IP address.
Judging by the amount of scans and other malicious traffic I see from
contaboserver, I wouldn't blame them from dropping traffic from that
particular provider.
Regarding M$ support, I'm slightly curious if they block by IP-range,
but when checking for a block, support searches textually for the IP
address.
ex: filter the whole 62.169.24.0/21, but support just greps for
'62.169.28.150' and finds no match. I wouldn't put it past them to do
just that.
Cheers,
On 9/3/25 13:13, Odhiambo Washington via mailop wrote:
Hello Team,
For days now, I am having the below problem with mail delivery to the M$
domains:
```
john...@hotmail.com <mailto:john...@hotmail.com>
host hotmail-com.olc.protection.outlook.com <http://hotmail-
com.olc.protection.outlook.com/> [52.101.9.18]
SMTP error from remote mail server after pipelined sending data block:
550 5.7.1 Unfortunately, messages from [62.169.28.150] 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.asp[truncated] <http://
mail.live.com/mail/troubleshooting.asp%5Btruncated%5D>
```
I raised this issue with my "ISP" - Contabo. Instead of them addressing
the issue, they asked me to contact MS via https://
support.microsoft.com/en-us/
supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75 <https://
support.microsoft.com/en-us/
supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75>.
MS of course responded and said they do not see any problem with my
IP address as shown below:
```
Hello,
Thank you for contacting the Outlook.com Deliverability Support Team.
I do not see anything offhand with the IP’s (62.169.28.150) that would
be preventing your mail from reaching our customers.
You may be able to find additional information on common delivery
questions at the _Outlook.com Postmaster Site_ <https://mail.live.com/
mail/postmaster.aspx>.
Here are some things that can help you with delivery:
* *_Junk Email Reporting Program (JMRP)_* <https://
postmaster.live.com/snds/JMRP.aspx?wa=wsignin1.0>*.*
* *_Join the Smart Network Data Services program (SNDS)_* <http://
postmaster.msn.com/snds/>**
* *_Return Path's IP Certification_* <https://www.validity.com/
products/returnpath/certification/>
The troubleshooting steps in this email are recommendations only.
Microsoft makes no guarantees that following these steps will guarantee
deliverability to Hotmail, MSN, Outlook.com, or Live.com customers.
For more detailed information about best sending practices to
Outlook.com users, please review _Outlook.com Enhanced Deliverability
white paper_ <http://download.microsoft.com/download/e/3/3/
e3397e7c-17a6-497d-9693-78f80be272fb/enhance_deliver.pdf>.
Thanks again,
Manjushri
Outlook.com Deliverability Support
```
Now, I am left wondering how to deal with Contabo to force them to
address the issue as an ISP and not pass the buck to the customer.
--
Best regards,
Odhiambo WASHINGTON,
Nairobi,KE
+254 7 3200 0004/+254 7 2274 3223
In an Internet failure case, the #1 suspect is a constant: DNS.
"Oh, the cruft.", egrep -v '^$|^.*#' ¯\_(ツ)_/¯ :-)
[How to ask smart questions: http://www.catb.org/~esr/faqs/smart-
questions.html <http://www.catb.org/~esr/faqs/smart-questions.html>]
_______________________________________________
mailop mailing list
mailop@mailop.org
https://list.mailop.org/listinfo/mailop
_______________________________________________
mailop mailing list
mailop@mailop.org
https://list.mailop.org/listinfo/mailop
