You don’t currently qualify for a Microsoft 365 Developer Program sandbox subscription

Hi iwata makiko, I realize how frustrating it must be to feel blocked from setting up a new sandbox, especially after you already went through the process of deleting your old account.

To fix the sandbox eligibility issue, sign in with your Outlook account at the Microsoft 365 Developer Program portal remember that only one sandbox is allowed per person and old accounts may take weeks to clear then contact Microsoft Support via the dashboard or Q&A forum to request unlinking of your phone number and a reset of eligibility providing both your old Gmail and new Outlook addresses along with the error message and while waiting you can try a different phone number or a work/school account but the most reliable solution is to let Microsoft reset your eligibility so don’t keep retrying document your request carefully and allow a few days for processing.

When you try to register your Outlook account for the Developer Program, does the error appear immediately after entering your details, or only after the system attempts to verify your phone number and eligibility?

Best regards
Lucky Charm