If you're using TB to get to your Microsoft email, your problem may be related to the fact that Microsoft just flipped the switch to stop accepting basic authentication (just username and password) on their website from applications - including older versions of MS Outlook and phone apps. I had this problem with 6 email accounts on Outlook 2019 which accessed email on Outlook.com. You can google: "Microsoft Outlook Basic Authentication" for more information. But if this is the cause, and you are using TB to access your email, all you should have to do is go to the setup for each of your email accounts on your computer in the latest version of TB (which supports advanced authentication) and change the authentication method to OAuth2. That is the modern authentication method that MS accepts now. You may have to also login to your Microsoft email account online to add 2 factor authentication on each account first. If the first step doesn't work, try the second step and retry the first one. I talked to several MS support techs before I got the correct steps. I cannot provide details about MSN because I have never used it. I use another Microsoft account: Outlook.com. Hopefully, this will provide enough information to get you moving in the right direction. Good luck!