Using Classic Outlook on Windows for personal email, calendar, and contact management
This code issue has been resolved by "In one recent case we discussed the user was having this same issue, but it got resolved using Authenticator." It solved the same issue in another post here in Answers. I assume you still have access to the MSA account, you might try adding Authenticator to your phone and adding it to your MSA security methods. This eliminates the code via email process.