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

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

This issue may arise due to one or more of the following reasons:

• The latest updates have not been installed.
• Outlook is being used by another process.
• Outlook is loading external content, like images in an email.
• A previously installed add-in is causing interference with Outlook.
• Your mailboxes have grown too large.
• The AppData folder is redirected to a network location.
• Office programs need to be repaired.
• Outlook data files are corrupted or damaged.
• The installed antivirus software is outdated or conflicts with Outlook.
• Your user profile is corrupted.
• Another program is conflicting with Outlook.

Many of these items can be automatically checked by Microsoft Support and Recovery Assistant.

Note that Microsoft Support and Recovery Assistant scenarios aren’t available for new Outlook for Windows.

To start the automated checks, follow these steps:

• Install the Outlook Advanced Diagnostics tool.

• Select Run when you are prompted by your browser.

• In the report that’s generated, review the items on the Issues found tab. For configuration details about Outlook, Windows, and your computer, review the settings on the Detailed View tab.

Further information = Outlook not responding error or Outlook freezes – Outlook | Microsoft Learn