Hello, @MOHAMMAD TADMEER ALAM,
Welcome to the Microsoft Q&A platform!
Based on your description, a user of yours could not get results as expected when searching his inbox in Outlook Web and Outlook applications. In addition to considering the browser, you can also try the following solutions:
1.For the Outlook application, select the Start button, select Settings > Update & Security, and then select Troubleshoot. Find and click Search and Indexing and click Run the troubleshooter. This will help to check the issue.
2.If there are no results, please verify the Indexing is complete by following the steps below:
- Start Outlook and click in the Search box.
- Select Search Tools > Indexing Status from the Search menu.
- When the Indexing Status dialog appears, you should see the screenshot below.
If the number of items did not decrease after indexing, continue to the next step.
3.Try to Fix search issues by rebuilding your Instant Search catalog and complete all the steps.
4.Try to re-create another Outlook profile and test it again according to Create an Outlook profile - Microsoft Support.
5.Try to Repair an Office application - Microsoft Support via Control Panel.
For more information to help you with this issue, please check this article as reference: Troubleshooting Outlook search issues and perform all the steps completely.
Hope the solutions and documents given above could be useful to you. Should you need more help on this, you can feel free to post back.
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Thank you for your support and understanding.
Best Wishes,
Alex Zhang