550 5.7.1 ERROR # Email rejected by hotmail.com and dbmail.com

This is the mail system at host miramont.bzh.

I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

               The mail system

[email protected]: host
hotmail-com.olc.protection.outlook.com[] said: 550 5.7.1
Unfortunately, messages from [] 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
2023-09-12T20:48:15.818Z 08DBB3C468EC886A] (in reply to MAIL FROM command)

My mail server ( is deditated and is not blacklisted by Microsoft
When i send mail to same user [email protected] all working fine
All reputation test is 10/10 with NO issue

any idea ? thanks for youyr help