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 Outlook Not Sending or Receiving Email 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

This happens to accounts that are configured in the iOS Mail app. Until you can install the Windows Update fix release, you can set a registry key that will cause Outlook to stop using the local Windows Search service. When this registry key is set, Outlook will use its own built-in search engine. The built-in search will display the message below to indicate it is not using the Windows Search service. To access the calendar shared with your Microsoft 365 for business account, you'll need to accept the invitation from Outlook on the web, iOS, or Android. 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.

Outlook Known issues in April 2023 updates

When you install Outlook, an Inbox repair tool (scanpst.exe) is also installed on your PC. The Inbox repair tool can resolve problems by scanning your Outlook data files, and repair corrupted OST in Outlook repairing errors. To use the Inbox repair tool, exit Outlook, and then follow the steps in Repair Outlook Data Files (.pst and .ost). If your antivirus software includes integration with Outlook, you may experience performance issues. You can disable all Outlook integration within the antivirus software.

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.

• Your user profile is a collection of settings that let you customize the computer appearance and performance.
• You must have at least three user accounts on the computer to complete these steps.
• For a list of antivirus software vendors, see Consumer antivirus software providers for Windows.
• Please install the Windows 10 Fall Creators Update to fix this issue.
• To access the filtering options faster, add them to your Quick Access Toolbar.
• We recommend that you move several items in your larger folders to separate folders, or that you archive those items by using the AutoArchive feature.

Outlook Known issues in May 2024 updates

To install the latest Windows and Office updates, click the link below. Your user profile is a collection of settings that let you customize the computer appearance and performance. It contains settings for desktop backgrounds, screen savers, sound settings, and other features.





User profiles help make sure that your personal preferences are used when you log on to Windows. As your mailbox size increases, more resources are required to open each folder. If you have a large number of items in any single folder, you may experience performance issues office 365 sync problems and login fixes during certain operations.