Login issue with Outlook Classic with Office 365 Family)?

Dear Dejan Janevski,

Thank you for reaching out in the Microsoft Q&A. I understand you're facing a frustrating login issue with Outlook Classic after a recent update, especially since your other Office apps are working fine. The error message you're seeing, "This username may be incorrect," is often misleading and usually points to a problem with your Outlook profile, not your login credentials. 

The fact that the problem started after an update and involved a new "Alias" account suggests that your original Outlook profile may have become corrupted. The best way to resolve this is to create a new Outlook profile and then add your IMAP account to it. This will leave your old profile intact but create a fresh connection that should bypass the corruption. 

How to Create a New Outlook Profile 

1. Close all Microsoft Office applications, including Outlook. 
2. Open the Control Panel. You can find it by searching for "Control Panel" in the Windows search bar. 
3. In the Control Panel, change the view to Large icons or Small icons (if it's not already). 
4. Find and click on Mail (Microsoft Outlook). A new window will pop up. 
5. In the "Mail Setup" window, click on Show Profiles.... 
6. Click Add... to create a new profile. Give it a simple name like "Dejan Outlook" and click OK. 
7. Follow the on-screen instructions to add your IMAP account to the new profile. You will need your email address, password, and the server settings (IMAP incoming and SMTP outgoing server addresses, port numbers, and encryption type) from your email provider. 
8. Once the account is added, go back to the "Show Profiles" window. At the bottom, change the option "When starting Microsoft Outlook, use this profile" to Always use this profile and select the new profile you just created from the dropdown menu. 
9. Click OK to save the changes. 

Now, when you open Outlook Classic, it will use the new profile, which should resolve the login issue. 

For a more detailed, step-by-step guide with screenshots, please refer to the following official Microsoft Support article: Overview of Outlook email profiles - Microsoft Support 

Regarding the "New Outlook" 

The new Outlook is a separate application that's still in development. It is normal that you could log in with your "alias" as that is tied to your Microsoft Account, but you will need to manually add your external IMAP account to it as well. The login issues you experienced in Outlook Classic should not affect how you add and use your IMAP account in the new Outlook. 

Please let me know if these steps help. We look forward to your response.  

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There is only the single login for an MS Office suite and its components.

Which Office suite?

Restart the PC, once fully loaded, repair Office,> Apps & Features>Select Office your version>Modify /Repair, once the repair completes re-test (Quick repair)

O365/Office when installed under a Win user admin account, and run from that admin account, auto logs in when the PC is started. There is no separate login for any component.

Win search for Word > Resulting shortcut > Rt click > Pin to task bar > start Word from that shortcut (hover mouse over the shortcut gives access to the 10 most recent docs)

Same for other core components.

Start eg Word open an old doc via recents/search