My son has been having the same problem for at least two weeks and maybe up to a month: Whenever he sends Murena email messages to anyone on outlook.com email, the messages bounce with the same type of error message @Andres reports from outlook.com. This has also been reported elsewhere: Can’t send email to Microsoft addresses - /e/OS Devices / Murena - /e/OS community, Not able to send mails to Hotmail accounts - Using /e/OS / Troubleshooting - /e/OS community, and Email rejected by outlook.com - Using /e/OS / Applications - /e/OS community.
Furthermore, my son has the same issue from his T2e and from his computer (both from webmail and an email client), regardless of what type of internet connection he is using. Yesterday, I followed the instruction in the bounce message: “Please contact your Internet service provider since part of their network is on our blocklist (S3150).” Our ISP checked everything on their end and noticed no blocks. They suggested that the problem is on the email sending server and that we should contact the email provider. Any updates on this problem?