Why does Microsoft continually *.. its clients, like me of 35+ years by making us pay for a service and then take it away the ability to use it... like Microsoft Business Basic not capable of using Outlook anymore????????

Microsoft 365 Business Basic still includes the Exchange Online mailbox and Outlook on the web/mobile, but it does not include the license required to use that work account by itself in new or classic Outlook for Windows.^1^

The message in the screenshot is therefore a licensing restriction, not an indication that the mailbox or paid email service has been removed. Microsoft documents this account-not-supported error for subscriptions that do not include Outlook desktop-app rights.^2^

Available options

1. Keep Business Basic and use Outlook on the web or mobile.
   Business Basic includes the web and mobile versions of Outlook. Open Outlook on the web through Microsoft 365 in a browser and sign in with the Business Basic work account.
2. Upgrade the user to Business Standard or Business Premium.
   Both include the desktop Microsoft 365 applications, including Outlook. Microsoft 365 Apps for business is also listed as carrying desktop-app rights, although mailbox licensing must still be maintained separately.^1^
3. Use another qualifying Microsoft 365 subscription already owned.
   If new Outlook contains any account licensed for desktop applications—such as Microsoft 365 Personal/Family, Business Standard, or Business Premium—the Business Basic mailbox can then be added as a secondary account.^1^ In new Outlook:
   1. Select Add subscription and sign in with the account that owns the qualifying subscription.
   2. Open View → View settings → Accounts → Your accounts.
   3. Select Add Account and add the Business Basic email address.^3^
   If the subscription belongs to a Microsoft 365 Personal or Family account, use that subscription owner’s Microsoft account—not the Business Basic credentials—when selecting Add subscription.

About switching back to classic Outlook

New Outlook may offer Help → Go to classic Outlook or a toggle for switching back.^4^ However, switching clients does not by itself add desktop-app rights. Classic Outlook also requires a qualifying desktop license when used with a Microsoft 365 organizational mailbox.^1^

If the account previously worked in desktop Outlook, check which subscription was activating that installation. It may have been a separate Personal/Family, Business Standard/Premium, enterprise, or perpetual Outlook license rather than Business Basic itself.

References

1. Licensing in new Outlook for Windows | Microsoft Learn
2. Supported accounts in new Outlook for Windows | Microsoft Learn
3. Add an email account to Outlook for Windows | Microsoft Support
4. Switch to new Outlook for Windows | Microsoft Support