Outlook blocks my server and delisting is disfunctional

Question

Hi,

I have delisted today and it does not work.

<******@outlook.com>: host     outlook-com.olc.protection.outlook.com[52.101.11.8] said: 550 5.7.1     Unfortunately, messages from [89.58.63.101] 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=11BAB3956FF1FFEA]     [SN1PEPF0002636A.namprd02.prod.outlook.com 2025-03-05T21:58:58.900Z     08DD59CABB760E1E] (in reply to MAIL FROM command)

Reporting-MTA: dns; server.stajl.page X-Postfix-Queue-ID: A347928405E X-Postfix-Sender: rfc822; ******@mo-heilmassage.at Arrival-Date: Wed,  5 Mar 2025 22:58:57 +0100 (CET)

I did that a few times before, then i started to send direct e-mail because it had no lasting result. Those e-mails are ignored.

The problem is the policy microsoft uses. If i rent a server from a company that is trustworthy and they have a problem with 1 customer out of thousands then microsoft blocks whole ranges of IP's which is utterly unfair because a lot of decent admins get a problem that way.

I am in this business for about 40 years now and i do not have to spell out the record that Microsoft has on security with its products. Much has improved, but as for e-mail, too much blocking is disruptive for businesses that is why i tell all customers to use an other solution then Outlook if they do not want to lose a lot of potential customers.

For your information i used to be the head of IT in a hospital, now i am a freelance consultant.

Regards,

Jan van Leeuwen, Stajl IT

Answer 1

Hi @Jan van Leeuwen ,

Welcome to our forum!

What's your account?

Based on my research on the error you provided, i found the official article to resolve it, please refer to it: Fix NDR error "550 5.7.1" in Exchange Online.

Hope to help you!

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Answer 2

Hi ChristyZhang-MSFT,

the problem will not be solved as long as microsoft/outlook blocks whole ranges of IP's including the IP-Adresses of decent admins.
I advise customers to refrain from using E-Mail-Addresses at outlook.com while they will lose their customers because of mircrosofts policy.

Regards,
Jan van Leeuwen, Stajl IT