"Outlook not responding" error or Outlook freezes when you open a file or send mail

Symptoms

When you open a file or send an email message in Microsoft Outlook 2010 or later versions, Outlook freezes, or you receive the following error message: 
Outlook not responding

Cause

This problem occurs for one or more of the following reasons:
  • You have not installed the latest updates.
  • Outlook is in use by another process.
  • Outlook is loading external content, such as images in an email message.
  • A previously installed add-in is interfering with Outlook.
  • Your mailboxes are too large.
  • Your AppData folder is redirected to a network location.
  • You have to repair your Office programs.
  • Outlook data files have become corrupted or damaged.
  • Your installed antivirus software is outdated, or it conflicts with Outlook.
  • Your user profile has become corrupted.
  • Another program conflicts with Outlook.
Note This issue may occur for one or more of the reasons in the "Cause" section. To fix this issue, you may need to follow one of several of the following troubleshooting steps. These steps are provided in a specific order based on how commonality and complexity, please follow these steps in the given order.

Resolution

To resolve this problem, make sure that your computer meets the Outlook 2016 system requirements, Outlook 2013 system requirements or Outlook 2010 system requirements. Then, try the following steps in the given order.
Step 1: Install the latest updates
Step 2: Make sure that Outlook is not in use by another process
Step 3: Check the problem which caused by external contents
Step 4: Investigate possible add-in issues
Step 5: Check whether your mailbox is too large
Step 6: Check whether your AppData folder is being redirected to a network location
Step 7: Repair Office programs
Step 8: Repair Outlook data files
Step 9: Check whether antivirus software is up-to-date or conflicts with Outlook
Step 10: Create a user profile in Outlook
Step 11: Perform a Selective Startup (advanced users)
Step 12: Create a Windows user profile (advanced users)

Next step

If the information in this Knowledge Base article does not help resolve your problem in Outlook 2016, Outlook 2013 or Outlook 2010, see the following resources for more information:
Properties

Article ID: 2652320 - Last Review: Mar 22, 2016 - Revision: 1

Outlook 2016, Microsoft Outlook 2013, Microsoft Outlook 2010, Microsoft Outlook 2010 with Business Contact Manager

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