[Other Accounts] I cannot add Hotmail/Outlook.com accounts through the "Add External Email" feature.
Microsoft has recently announced the discontinuation of support for basic authentication in Exchange Online, starting from October 1, 2022.

Due to this security enhancement policy implemented by Microsoft, we regret to inform Exchange-based email users that the "Add External Email" feature is no longer available.

However, if you don't use Exchange-based email, you can still utilize the "Add External Email" feature as usual for Hotmail/Outlook.com accounts.

For more detailed information, please refer to the Microsoft technical support document.