Hi sangram.aglave, first please make sure that you have IMAP access enabled in your outlook settings: https://outlook.live.com/mail/0/options/mail/forwarding

Now open Thunderbird and click on "Email" under "Set Up Another Account" Enter your name and the Email address. Click on "MANUAL CONFIGURATION" underneath the Email address field.

Enter the following details: Protocol: IMAP Hostname: outlook.office365.com Port: 993 Connection security: SSL/TLS Authentication method: OAuth2 Username: YourUsername@outlook.com

Do not click on continue! Instead, click on "ADVANCED CONFIG" Click on "OK" in the dialog that opens. Close the Account Settings tab Click on Inbox, so that your mails and folders load.

Everything should work now.

It solved my problem but what is strange is that Mozilla Thunderbird never recorded or asked for my outlook password.

Doesn't work on my side. I have 2 microsoft email account (one live.ca and one hotmail.com) and they both don't work. I was able to add them in Outlook desktop app and EM Client (a non open source software i'd rather not use) through IMAP with success. IMAP is activated in both accounts and as per Microsoft documentation the server is supposed to be outlook.office365.com on port 993. eM Client magically discover IMAP settings to imap-mail.outlook.com instead. Thunderbird opens an OAuth page and then it redirects from microsoftonline.com to localhost and fail with "Unable to connect".

i am unable to send emails now.

this is a major problem. It did not solve the problem

In the original question there are really 2 problems. 1. Problem which seems to have been overlooked is that even if the experimental "Account Hub" is deselected I am still directed to it when trying to add a new account. I hear rumours that it is buggy and should be avoided at the moment. Surely I should be reverted to the old procedure? 2. The authentication error is present even though it says that a secure connection to the server has been established. In my particular case I am trying to add a second outlook account. The first one works fine - the new one fails (The server settings are identical in both cases.)