Microsoft Outlook 365 filter feature not working

Question

We are experiencing a search issue in the New Outlook as well as Outlook on the Web.

The problem affects only one user within our Microsoft 365 tenant. Other users are not experiencing any issues.

Search either returns incorrect results or does not work at all. The issue occurs across multiple devices (different PCs and web browsers) when using the same user account, which suggests this is likely a mailbox-level or server-side indexing issue rather than a device-specific problem.

This looks like a mailbox indexing problem. Could you please advise if there is any way to reindex the mailbox for New Outlook or Outlook Web? Is there any method to trigger a server-side search reindex for a specific user?

Thank you for your assistance.

Answer 1

Hello IT-TECH - Matej Tkáč,

Thank you for posting your question in the Microsoft Q&A forum.

If filter/search is failing for only one user and reproduces in both New Outlook and Outlook on the web (OWA) across multiple devices, that strongly suggests a server‑side mailbox indexing issue (Exchange Online) rather than a local Windows Search problem.

With the mailbox search error, I find several workarounds that you can double-check it first:

1/ Use filters to narrow your search and show older email messages:

In new Outlook, when searching for older results, you can use filters to narrow your search criteria. If new Outlook finds too many results, older items may not be displayed.

You can adjust the default scope to Current Folder by going into Settings.

Online Archives are searched, and results are included automatically.

• Multi-account search is not currently supported. To search multiple inboxes, you need to select each account and search in All Folders.
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2/ Outlook search returns incomplete results, or search can't find older emails:

• Make sure to include Deleted items folder and increase the sync slider to download past emails by following this article: Troubleshooting Outlook search issues - Microsoft Support.
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• In the other hand, I also find an article which can help you to verify and rebuild the search index on server side in Microsoft Exchange Online: Rebuild search index of a mailbox in Exchange Online | Microsoft Community Hub.
• Disclaimer: The steps and suggestions are based on community‑shared troubleshooting experiences. Please proceed at your own risk and always consider opening an official Microsoft Support ticket if you are unsure or if the issue affects production systems.

Additionally, there is an idea to fix search issues by rebuilding your Instant Search catalog, see more details in here: Fix search issues by rebuilding your Instant Search catalog - Microsoft Support.

Note: Please understand that as a forum moderator, my primary goal is to provide helpful guidance and support through general troubleshooting steps. While I don’t have access to internal systems or test devices required to resolve backend/account issues, I truly appreciate your understanding of these limitations.

Thank you for choosing Microsoft, and I am looking forward to your response. If anything is unclear, please don’t hesitate to reach out to me.

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