You have received an email notification that states the following: “A new device has been used to sign in to your Nintendo Account”. The email might include information about an unknown device or geographical location.
You received an unexpected "[Nintendo Account] Email address verification" email.
Your Nintendo Account has been compromised or accessed by an unauthorised user.
What to do
Change your Nintendo Account password.
Change the password associated to your Nintendo Account.
If you don’t remember your Nintendo Account password or log-in information, reset your password.
If your Nintendo Account is linked to a Nintendo Network ID, you can change the NNID password on a Wii U or Nintendo 3DS family system.
If you suspect a linked NNID has been compromised, you can also unlink it from your Nintendo Account to prevent further access.
Sign out of all devices associated with your Nintendo Account.
Sign in to your Nintendo Account on the Nintendo Account website, select "Sign-In and Security Settings" in your account profile, and select "View" beside your sign-in history. Select "Sign out on all other devices".
This will disassociate the Nintendo Account from any devices on which it was previously signed in. You will need to sign in again on each device using the new password to associate your Nintendo Account again.
Set up two-step verification security for your Nintendo Account.
Two-step verification adds an additional layer of security that can help prevent unauthorised access to the account.
Create a Sign-In ID for your Nintendo Account that only you know, and change your Nintendo Account sign-in method preference to "Sign-In ID only".
This can help prevent others from using your email address to try to sign in to your account without your permission.
If your Nintendo Account is linked to Google or Apple it is recommended that you change the password for those accounts.
It is possible that one of those accounts was compromised, which allowed access to your Nintendo Account.
Visit the appropriate company's website and use their help area for instructions about how to update your password.
If you suspect a linked Google or Apple account has been compromised, you can also unlink it from your Nintendo Account to prevent further access.
If your Nintendo Account is linked to a Nintendo Network ID, and you suspect that the Nintendo Network ID was compromised, it is recommended that you change its password.
If you are unable to change the Nintendo Network ID password, you can unlink it from your Nintendo Account.
If you suspect that your email address inbox has been accessed by an unauthorised user, please contact the email provider for assistance with recovering your email account.
You can also contact the Nintendo Customer Support Team here.