Outlook Classic Storage Issue Affecting Multiple Users

Question

We are currently experiencing an issue with Outlook Classic where users are encountering storage-related problems and are unable to work normally within the application.

Notably, the same mailboxes function correctly in New Outlook, and users do not experience these issues when accessing their accounts through the new client. The problem appears to be affecting multiple users rather than isolated accounts.

Could you please advise on the root cause and provide recommendations to resolve this issue?

Answer 1

Hi @Gundappa Yerolla ,

I hope you're doing well.

Based on my testing, Classic Outlook is currently working as expected in my environment. Additionally, I have not found any official documentation or known issue published by Microsoft that confirms a widespread storage-related issue affecting multiple users in Classic Outlook for Windows at this time.

To help identify the root cause of the issue, could you please provide the following details?

• Could you provide the exact error message you are seeing, or a screenshot of the issue?
• What is the version and build number of the affected Outlook Classic client?
• Are the affected mailboxes hosted in Exchange Online or an on-premises Exchange Server environment?
• Does the issue affect all users, or only a subset of users?
• What is the approximate size of the affected mailbox(es)?

In the meantime, you may want to try the following troubleshooting steps:

1. Confirm Outlook Status

• Open Classic Outlook.
• Select the Send/Receive tab and make sure that Work Offline mode isn't enabled.

• If it shows Logged Out, Password Required, or Login Attempt, it indicates that the account is not properly authenticated.

2. Repair Microsoft 365 Apps

• Close all office apps completely.   
• Go to Control Panel > Program > Programs and Features   
• Right click on the Microsoft Office you've installed > Change.   

• Select Quick Repair first (fast and doesn’t require internet).   
• If the issue persists, run Online Repair (requires internet and takes longer).  

3. Create a new Outlook profile

• Close Outlook.
• Open Control Panel > User Accounts > Mail (Microsoft Outlook).
• Click Show Profiles.

• Click Add... to create a new profile.

• Add the account again.
• Start Outlook using the new profile.

Please also let me know the result after trying all the steps above.

Looking forward to your response so that we can solve this problem together.