Stuff to check out - I'll list everything just in case this gets read by anyone needing information.

In Microsoft account. Please logon to Microsoft account and check what is set up as 'primary'. Microsoft consider all email addresses as alias. Microsoft now say you would need same password used to access Microsoft account for the email addresses. Whatever email address has been set up as 'primary' is the only email address you can use to send emails via a third party email client such as Thunderbird. So if you had two email addresses eg: outlook.com and hotmail.com, if outlook.com was the 'primary' then both outlook.com and hotmail.com email address can only send - smtp - using outlook.com email address. To ensure you get emails coming back to the correct email address, you would need to set up the Hotmail account 'Reply-to Address' as the hotmail email address. If you only have the one 'hotmail' address then I presume it's also primary, so smtp should be ok.

Check this on computer:

Firewall: Access Firewalll which might be the defaul on computer or controlled by an Antri-Virus you installed. Make sure Thunderbird program has been set up as an allowed program to ensure nothing is blocked.

VPN: Check computer for a VPN. Some AV programs do offer a VPN option and in some cases I've discovered it gets enabled utomatically. Many servers do not like VPN and think you are a hacker as it hides the IP address. Switch off VPN or create a slpit tunnelling and set up Thunderbird to use it.

Localhost: Check computer to see if something is using the localhost. Typically, those who manage websites will use eg: Apache Xampp - it uses localhost. You would need to switch it off whilst setting up the accounts in Thunderbird; you can enable it again afterwards.

Check In Thunderbird

• Settings > Privacy & Security
• Web Content
• Select 'Accept cookies from sites'
• Click on 'Exceptions' button
• Enter this : https://accounts.google.com (for the gmail accounts) and http://hotmail.com, http://outlook.com, http://office365.com, http://www.msn.com (to cover the microsoft accounts.)
• Click on 'Allow
• Click on 'Save Changes'

• Whilst in that area - scroll to Passwords section
• click on 'Saved Passwords'
• If you see any mention of the account you are trying to set up where 'username' = email address of account - select the relevant lines and click on 'Remove'
• Click on Close

Switch off the following as it's still experimental.

• Settings > General
• Account Hub
• uncheck this checkbox: 'Create accounts in the new Account Hub'

Then create the mail account

• Menu app > New Account > Email
• Enter name
• Enter full email address
• Enter password
• Select checkbox to remember password.
• Click on 'Continue'

Thunderbird by default will look for the IMAP server settings for the relevant server.

Microsoft account incoming -

• Server Type: IMAP Mail Server
• Server Name: outlook.office365.com
• Port 993
• User Name: xxxx@hotmail.com (example)
• Connection Security: SSL/TLS
• Authentication Method: OAuth2

SMTP

• Description: type email address = username
• Server Name: smtp.office365.com
• Port: 587
• User Name: xxxx@hotmail.com (example)
• Authentication method: OAuth2
• Connection Security: STARTTLS

Assuming all is ok click on 'Done'

You should then get the pop up browser type window. It will ask you to confirm you really are you and the then askif you want to allow Thunderbird access to server.

Then an OAuth token gets created and stored in the same place as all other passwords.

Thanks for the response. I have worked through these steps and am still having the same issue

• Firewall open for thunderbird
• No VPN used
• nothing running on localhost that I can see
• Cookies accepted with exceptions
• No saved password
• Account Hub off

Still getting a blank dark blue window pointing at the OAuth URL.

Is there any way to use an external browser for the OAuth validation part? Considering I had to use general.useragent.compatMode.firefox for the GMail accounts, there might be something going on with the internal browser?