Using New Outlook on Windows for personal email, calendar, and contact management
Hi, Arturo Iannelli
Good day!
Thanks for posting into our community.
According to your description, the issue of your concern that you've got an NDR - Non delivery report when sending out the emails.
For troubleshooting this issue, please allow us to double confirm below information and these will help us to narrow down the issue for you. Thanks for your understanding and cooperation.
- First of alll, would you please tell us whether you're using an IMAP account or an Exchange account?
- Have you ever tried to send on OWA - Outlook Web App and check if there's a same issue or not.
- Would you please capture a screenshot of this prompted error with us that the detailed information for this given error will give us some hints.
Thanks for your attempts and sharing, looking forward to your new updates. And please feel free to contact us, we will stick with you.
Hope you all the best!
Microsoft Community Moderator.