Sending from murena.io email to an outlook account

Hello,

Since a couple of weeks I can’t send emails from my murena.io email to outlook accounts as I get a message: “parts of your email domain are on our block list.”

Pls help. This is a very urgent issue to me.
Thx

Regain your privacy! Adopt /e/OS the deGoogled mobile OS and online servicesphone

A forum Search :mag: reveals Murena IP blocked by Microsoft

and Oulook.com pbms?

and Hotmail mails not accepted by e.email

and Microsoft announces new email requirements for bulk senders - Red Sift Blog

and this link https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook’s-new-requirements-for-high‐volume-senders/4399730 contains an update of 29 April 2025

An indicator of May 5th 2025 “barriers” immediately above would be

The rejected messages will be designated as

“550; 5.7.515 Access denied, sending domain [SendingDomain] does not meet the required authentication level.”

I know. But new is: it worked for some days but now fails again

Still failing on Hotmail

sm@hotmail.com>: host
hotmail-com.olc.protection.outlook.com[52.101.9.27] said: 550 5.7.1
Unfortunately, messages from [135.181.6.248] 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
Troubleshooting. [Name=Protocol
Filter Agent][AGT=PFA][MxId=11BB3FC9E661B5CC]
[BL02EPF0002992A.namprd02.prod.outlook.com 2025-06-06T11:53:02.189Z
08DD9FE4F9656B4B] (in reply to MAIL FROM command)

S3150 is the keyword you’d find many threads for in the forum. The gitlab issue for this is at

if the contact is friends&family, there is a workaround noted in the issue

I have the same problem. Very annoying.
Too may problems with e.email service.
First, some months ago, unable to send end receive mails during several weeks, and now that.
I will switch to something else as soon as possible.