The email address [email protected] (edited email) is valid and fully operational on Microsoft 365.
It appears to be functioning properly with most other email providers, such as Gmail and Outlook, but is encountering issues specifically with Hestia.
Since all users are configured on Microsoft 365, I have not created them on Hestia.
By configuring the “accept senders” How can I disable the reverse DNS lookup security check in Hestia/Exim?, I was able to resolve the issue of emails sending from Microsoft 365 to Hestia. However, emails sent from Hestia to Microsoft 365 are still not going through.
I sent you the logs for your review.