Dear Satoko,
Thank you for reaching out to the Microsoft Community. I hope you're having a great day!
Based on the error you shared, it appears that the issue is related to the client's email configuration.
Please note that this type of problem typically needs to be resolved on the recipient’s side. The error message indicating that the email address is “not verified” suggests that their email system may have restrictions or incomplete setup, such as domain verification issues or mailbox provisioning delays.
Recommended Action:
I suggest asking your client to contact their IT support team or email administrator to verify that:
- Their email address is fully set up and active.
- There are no restrictions or verification issues on their account.
- Their domain and DNS records (like SPF, DKIM, DMARC) are correctly configured.
Unfortunately, as the sender, you won’t be able to verify or fix this from your side. But once their IT team resolves the issue, your emails should go through normally.
If your client does not have an IT team*, they can also contact* Microsoft Support directly through https://support.microsoft.com/contactus for further assistance.
I appreciate your understanding. Should you have any further questions, please let me know.
Best regards,
Ian Ng - MSFT | Microsoft Community Support Specialist.