The loading of unregistered MAPI services has been disabled by default to make Outlook more secure. To edit a shared calendar, go online to your own Outlook.com calendar, open Calendar for Windows 10, or use a mobile device. Maybe you've added a new program to your computer that doesn't get along with Outlook, or your system has a virus. Regardless of the specific cause, there are several key troubleshooting fixes to try that might help. If your antivirus software isn't up-to-date, Outlook may not function correctly. Outlook stores certain data, such as email signatures and the spelling checker dictionary, in the AppData folder.

Outlook known issues in the October 2019 updates

If you manually type in the secondary connected account email address in the "From" field, the email is sent as "On behalf of" your primary Outlook.com account. When you start Windows normally, several applications and services start automatically and then run in the background. A Selective Startup or "clean boot" process can help you identify problems that are caused by application conflicts. The issues documented in this section have been reported after installing the recent Microsoft Outlook Email Repair Tool Online updates listed below. We're investigating the issues and will update this page when a fix is available. In the meantime, please use the workarounds suggested for each issue.

Outlook Known issues in December 2024 updates

Many of these items can be automatically checked by the Classic Outlook Advanced Diagnostics troubleshooter. Right-click the folder, and then click Properties to check your permissions for the folder. See the folder owner or your administrator to change your permissions. Another options is to use the Filter Email button on the ribbon.

Outlook Known issues in April 2023 updates

If the check box is cleared, the service or startup program doesn't run when you restart the computer. You can also add the secondary connected accounts (Gmail, Yahoo, etc.) in Outlook.com as additional accounts in the Outlook resolve Outlook not sending emails fast profile. You might need to set Windows Update to automatically download and install recommended updates. Installing any important, recommended, and optional updates can often correct problems by replacing out-of-date files and fixing vulnerabilities.

VBScript does not run or you receive malicious code warning when using a custom form for Outlook

If the network is performing slowly, Outlook must wait for read and write operations to the AppData directory to finish. To manage your mailbox by reducing the size of the Outlook data file, see Reduce the size of Outlook Data Files (.pst and .ost). Although add-ins can enhance your user experience, they can occasionally interfere or conflict with Outlook.

• This can be exploited by creating a file together with an OLE object in such a way to cause MAPI to load a DLL from a network share when the OLE object is activated.
• If the check box is cleared, the service or startup program doesn't run when you restart the computer.
• After updating Office, you may experience a brief flashing window every hour, which triggers the OfficeBackgroundHandlerRegistration task to start running.
• Outlook 2016 freezes when you try to preview an Excel file that's attached to an email.
• If you've already clicked the Accept button in Outlook 2016, you won't be able to re-accept the invitation from another Outlook application.
• Download the latest updates by visiting your antivirus software vendor's website.
• If the network is performing slowly, Outlook must wait for read and write operations to the AppData directory to finish.
• To edit a shared calendar, go online to your own Outlook.com calendar, open Calendar for Windows 10, or use a mobile device.

Outlook Known issues in May 2024 updates

Or, you can disable any antivirus software add-ins that are installed in Outlook. If you have email messages in an email program, you must import your email messages and addresses to the new user profile before you delete the old profile. If everything is working correctly, you can now delete the old profile. In System Configuration, if you select a check box, the related service or startup program runs when you restart the computer.

Can't open Enterprise Vault items

Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. If you use the cloud-based Microsoft how to fix Outlook not opening today 365 on a PC or Mac, the automated Support and Recovery Assistant tool can diagnose and fix many issues, including Microsoft Outlook not starting. You may have to contact your antivirus software vendor to determine how to configure the software to exclude any integration with Outlook or to exclude scanning in Outlook. For a list of antivirus software vendors, see Consumer antivirus software providers for Windows. If the problem doesn't occur after you restart Outlook, one of the add-ins is likely the cause of the problem. Restore the add-ins one at a time until the problem does occur to determine which add-in is causing the problem.