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on February 3, 2026
If Outlook Desktop fails to connect, try these steps before escalating the issue to the ET&S Help Desk. If you have Outlook in your startup folder, remove the shortcut from the startup folder. Restart Outlook and try to reproduce the problem. Find solutions to common problems or get help from a support agent. To update your password in Outlook, see Change or update your email password. If you're having problems setting up your email in classic Outlook, we want to help.
After updating Office, you may experience a brief flashing window every hour, which triggers the OfficeBackgroundHandlerRegistration task to start running. In this case, sign in to the Microsoft 365 portal by using your administrator credentials, and then select service health to determine whether other customers are experiencing the same issue. If other customers are experiencing the issue, the issue should end when the service-interrupting event is resolved. If you’d like to share any feedback about this article, please let us know.
If Outlook is configured to connect to the Exchange mailbox in Online mode, an .ost file is not used. To adjust the number of days of data that are synced for shared folders, add the following registry values. You can limit the synchronization window that’s used for calendar folders to reduce the number of items that are stored locally in your calendar folders.
Sometimes, when Outlook isn’t working right, a simple restart can help. When you turn your computer off and on again, Outlook and your computer may solve many problems. As a result, it helps to clear out any issues or things that might be causing trouble, like when you clean up a messy room.
Are you having trouble starting Outlook or receiving "Cannot start Microsoft Outlook. Cannot open the Outlook window" error messages? We can fix the problem for you, or you can use the troubleshooting steps we're providing below to help resolve these startup issues. Here's the deal, when Outlook manages to open, all the files you delete will automatically be recreated. It gets better because you also resolve all the step-by-step Outlook troubleshooting Outlook opening issues. If the in-box Program cannot fix the corrupted Outlook PST files, you can also try Wondershare Repairit for Email.
The built-in step-by-step Outlook troubleshooting back-off mechanisms in the indexing component of Windows Search or WDS pauses the indexing of Outlook data when the system is under heavy use. The easiest way to let the indexing finish is to leave Outlook running overnight.Additionally, you can reduce performance issues by running Outlook in Cached Exchange Mode. In this mode, Windows Search or WDS searches the local copy of the mailbox instead of the mailbox content on the server. I even reduced mailboxes sizes and that didn't help, I setup a new user (albeit existing PC but new windows profile), and he is having the same issues. If the mailboxes open automatically after removing them and restarting Outlook, they may be auto mapped. This setting can be changed by an Exchange admin by submitting a request via Jira and including the usernames of the client and the usernames of the mailboxes that need to be removed.
There are quite a few different causes for this, but one of the most common is a defective add-in. Here’s how to disable add-ins in Outlook even when it keeps crashing. You have successfully created a Distribution Group. The maximum number of distribution group members is 100,000 members, and the recipient rate limit is 10,000 recipients per day. Step 1 - The hard limit of recipients for a single email message is 300. Reduce the number of recipients for a single email to less than 300.
If creating a new profile solves your issue, you can return to the Show Profiles dialog and delete your old profile. If you try to delete or move a large number of messages at once, Outlook can appear to freeze, but really, it's working behind the scenes. If Outlook is performing some operation on hundreds or thousands of messages at once, it might appear to be stuck. Give Outlook a few minutes to finish the process and it should start to work again. If Outlook isn't stuck at a screen that says "Processing," or this didn't resolve your issue, continue to the steps below. Use the classic Outlook startup troubleshooter to diagnose and fix several common classic Outlook for Windows issues for you.
Each folder will be listed with its size and number of messages. 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. To access the filtering options faster, add them to your Quick Access Toolbar. Another options is to use the Filter Email button on the ribbon.
If it’s an RDS server and the cache is also on the server, if the server crashes, reboots abruptly, is full, there are many reasons. Instead of removing the profile, remove the OST file and let it recreate. Compatibility mode is suitable for older software with Windows 10 that fail to run normally.