Why can't I start new email messages, insert attachments, or close out of my email account without Ctrl+Alt+Delete and shutting down the task?????

Hi @Union Bay Painting, 

I hope you are doing well today. 

From your description, you are using classic Outlook on your PC and you cannot start a new email, insert attachments, or close Outlook unless you end the task, while Outlook on the web works normally.  

Thank you for sharing the details, including that your mailbox is under the storage limit and that the issue only occurs in the desktop app. Since Outlook on the web works as expected, the account and mailbox service are functioning correctly, so the most likely cause is a desktop specific component such as an add-in, a local Outlook profile setting, or the local desktop cache becoming unresponsive during compose, attach, or exit actions.  

Please follow the steps below in order 

1/ Check whether an add-in is causing the hang by using Safe Mode, then disable add ins 

Safe Mode starts classic Outlook without loading add ins, therefore it is the fastest way to confirm whether an add-in is blocking the compose window, the attachment picker, or the close action.  

• Close Outlook fully.  
• Start Outlook in Safe Mode using the Microsoft instructions in the link below.  
• While in Safe Mode, test three actions in this order: create a new email, attach a small file from your desktop, then close Outlook. 
• If Safe Mode works correctly, switch back to normal mode and disable add ins, then restart Outlook.  
  • Open Outlook, then go to File, Options, and Add ins.  
  • Disable all COM Add ins, then restart Outlook and test again. 
  • Re enable add ins one at a time, restarting Outlook after each one, so the specific add in that triggers the issue can be identified.  
• References: 
  • Open Outlook in safe mode 
  • Outlook crashes or stops responding when used with Microsoft 365 

2/ Create a new Outlook profile to refresh local configuration 

If Safe Mode does not change the behavior, the next best step is creating a new Outlook profile, because a profile stores your Outlook accounts, data files, and settings, and a damaged profile can cause repeated hangs in the desktop app even when the mailbox is healthy.  

• Close Outlook.  
• Create a new Outlook profile by following the Microsoft steps in the link below.  
• Add your email account to the new profile, then open Outlook and allow time for the mailbox to finish syncing before testing New Email, Attach File, and Close again.  
• Reference: Create an Outlook profile 

3/ Repair Microsoft 365 apps, then update Office to the latest build 

If the issue continues, repairing Office can replace damaged app components, and updating Office can apply stability fixes that frequently address Outlook hangs and freezing.  

• Close all Office applications.  
• Run a repair of your Microsoft 365 or Office installation by following the Microsoft instructions, starting with Quick Repair and then using Online Repair if needed.  
• After the repair completes, update Office to the latest version using the Microsoft steps, then restart the PC and test Outlook again.  

Reference: Repair an Office application 

I hope this information is helpful. Please follow these steps and let me know if it works for you. If you have any updates regarding the issue, please feel free to share them with me.          

Thank you for your patience and your understanding. Wishing you a smooth rest of your day. 

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have any extra questions about this answer, please click "Comment".             

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.  

Because Outlook works online but not in the classic Windows app, the issue is with the local Outlook installation or profile, not storage or the account itself.

Try these steps in order on the PC where classic Outlook is installed:

1. Restart Outlook cleanly
   • Open Task Manager (Ctrl+Shift+Esc).
   • On the Processes tab, select Microsoft Outlook and choose End task so Outlook is fully closed.
   • Start Outlook again and test New Email, inserting attachments, and closing Outlook.
2. Check for oversized or stuck messages
   • In Outlook, go to the Outbox folder.
   • Open any stuck messages, especially those with large attachments (over about 20 MB).
   • Remove large attachments or delete the stuck message, then try sending again. Large attachments can block sending and cause Outlook to misbehave. For guidance on large attachments, see I can't send or receive messages in Outlook.
3. Repair or reset classic Outlook
   • If the app still freezes when starting new messages or adding attachments, follow the general troubleshooting guidance for Outlook for Windows:
     • Close Outlook.
     • Restart Windows.
     • Open Outlook and test again.
   • If problems persist, follow the steps under Troubleshoot Outlook for Windows issues to repair or reinstall Outlook for Windows.
4. If using new Outlook instead of classic
   • If the PC is actually running new Outlook for Windows (toggled from classic), restart it via Task Manager as above.
   • If that does not help, uninstall and reinstall new Outlook as described in Troubleshoot Outlook for Windows issues.
5. If attachments specifically are failing
   • Confirm that attachments are not exceeding provider limits (for example, messages with attachments larger than about 20–25 MB can cause send issues).
   • For large files, attach them as OneDrive links instead of direct attachments.

If none of these steps resolve the freezing and inability to start new messages, contact Microsoft support from Outlook.com or via the Outlook support options so the profile and installation can be checked in detail.

References:

• I can't send or receive messages in Outlook
• Troubleshoot Outlook for Windows issues
• Troubleshoot attachment problems in Outlook for Windows
• Unable to attach files in Outlook.com
• Classic Outlook crashes opening or starting a new email