Hotmail e-mails coming in return

[rbbekkhus]

These last days, I have troubles sending e-mails from my vivaldi.net to any hotmail adress. I can send e-mails to the same adresses from all my other e-mail providers.
I get:

<[hotmail_user]@hotmail.com>: host
    hotmail-com.olc.protection.outlook.com[104.47.57.161] said: 550 5.7.1
    Unfortunately, messages from [31.209.137.12] 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.
    [DM6NAM11FT061.eop-nam11.prod.protection.outlook.com] (in reply to MAIL
    FROM command)
Reporting-MTA: dns; smtp.vivaldi.net
X-Postfix-Queue-ID: 1917BBD040
X-Postfix-Sender: rfc822; [email protected]
Arrival-Date: Fri,  4 Mar 2022 09:00:52 +0000 (UTC)

Final-Recipient: rfc822; [email protected]
Original-Recipient: rfc822;[email protected]
Action: failed
Status: 5.7.1
Remote-MTA: dns; hotmail-com.olc.protection.outlook.com
Diagnostic-Code: smtp; 550 5.7.1 Unfortunately, messages from [31.209.137.12]
    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.
    [DM6NAM11FT061.eop-nam11.prod.protection.outlook.com]

//MODEDIT: added code block, removed e-mail addresses

[DoctorG]

@rbbekkhus I pinged Vivaldi mail server admin to check.

Microsoft was already contacted and has now to remove Vivaldi mail server from their block list.

[Ayespy]

This is not a Vivaldi Chats subject. Moving to Support and Troubleshooting.

"Vivaldi Chats

A place for general Vivaldi related discussions, polls and more.

To report and find solutions to issues, please visit the Support and Troubleshooting category.

To share your ideas about features that should get implemented in Vivaldi, please post in the Feature Requests category.

For topics not related to Vivaldi, please go to the Chit-Chat category.

[Pesala]

Seeing this issue still for Hotmail and GMX.

[Pesala]

Any update on this? I am still unable to send emails to a Hotmail address.

[WildEnte]

@pesala I think this is the same issue discussed here -> https://forum.vivaldi.net/topic/72494/sent-messages-do-not-reach-recipient-account/45?_=1650738478493

[Pesala]

@wildente It looks like the same issue. I didn't find it in a search for Hotmail.