Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi Steve,
Thank you for posting, I am here to help you. If the old mail was locked out can you remember using an Authenticator app to log in on this old mail before.
If you can't sign into your Old Microsoft account / Outlook mail most issues can be identified by our sign-in helper tool.
Click on this link: https://go.microsoft.com/fwlink/?linkid=2214157
The tool will ask you to enter the email address or mobile phone number you're trying to sign in with and check the details you provide. If we detect a problem with your account, we'll tell you what you need to do to solve the problem. If we don't detect any problem, we'll guide you through how you can help yourself.
For more information you can check this article from Microsoft: I can't sign in to my Microsoft account
looking forward to helping you out. If you need more help please let me know. If the answer is helpful, please click "Accept Answer".
Best regards,
Jansher