You may be aware that recently Microsoft changed the Authentication Method when it comes to using third party email clients eg: Thunderbird. However, they have also altered what password to use and what email address can use the SMTP. Read on: '''1.''' Your microsoft account and your hotmail/outlook/msn/live account all need to have the same password. So all your microsoft accounts need to be using same password. You may have other accounts which use the outlook server. Info at this link says: * https://support.microsoft.com/en-gb/office/how-to-sign-in-to-hotmail-c378938b-c0eb-40c1-b99e-338dd9e776a8 ''Can't sign in to Hotmail or Outlook.com?'' ''Notes: Your Hotmail or Outlook.com password is the same as your Microsoft Account password.'' You must logon to the microsoft webmail account via browser to sort it out. Once all your accounts are using same password..... '''2.''' In microsoft account accessed via a browser If you have more email addresses or hotmail addresses etc , microsoft now regard one is 'primary' and all others are alias to the account. This is not a problem when it comes to receiving mail, but can be an issues when you want to send. When it comes to 'sending' - that is smtp in Thunderbird - it can only send using the 'primary' email address. You can choose what you want to be set as 'primary', but whatever email address you set up as 'primary' - only that email address can be used for SMTP. So if you want to send using @dbmail email address then make sure it is set up as the primary email address. But then if you have an outlook.com account as well, it will only be able to send using the dbmail primary email address. So choose the email address which you want to set up as 'primary'. '''3. '''In Thunderbird, Cookies must be enabled in order to set up Oauth. * Settings > Privacy & Security * Check under Web Content - * Select: 'Accept cookies from sites' * Accept third party cookies' 'Always' * Click on 'Exceptions' button next to Accept cookies from sites to make sure you are not blocking cookies from Microsoft sites, such as :hotmail.com, outlook.com, office365.com, www.live.com, www.msn.com '''4.''' In Thunderbird....When creating account or if account is created but you need to check server settings: This is just an example where the username is for hotmail but it can be for any email address account in the microsoft account. Account Settings must use the following: Server Type: '''POP''' Mail Server * Server Name: outlook.office365.com * Port 995 * User Name: xxxx@hotmail.com * Connection Security: SSL/LTS * Authentication Method: OAuth2 Server Type: '''IMAP''' Mail Server * Server Name: outlook.office365.com * Port 993 * User Name: xxxx@hotmail.com * Connection Security: SSL/LTS * Authentication Method: OAuth2 '''SMTP:''' * Server Name: smtp.office365.com * Port: 587 * Connection Security: STARTTLS * Authentication method: OAuth2 * User Name: example@hotmail.com (Please note this must be whatever email address is set up as the 'primary' email address) Once you have all these settings and got the password sorted. Restart Thunderbird When you get the Microsoft pop up window asking for password, type it in and click on 'Sign in'. You may then get another window asking to allow Thunderbird access to server - click on 'Accept'

Others has similar issue when using a email address which used the outlook server. This was back at a time when I was just sorting out what was going on as Microsoft was not exactly being helpful. https://support.mozilla.org/en-US/questions/1465652#answer-1680651 https://support.mozilla.org/en-US/questions/1451659?page=4#answer-1680355