Outlook 2016 Search Glitch: Fix with Registry Tweak

Grab your coffee and do a double take because it’s 2025, and Outlook 2016 users are still out there dealing with bugs. This time, the issue strikes where it hurts the most: Search. Microsoft has confirmed some users of Outlook 2016 have been pulling their hair out after noticing that their inbox search results come up borked—missing the sender information and marking email threads as unread. Never fear, the Registry Editor cavalry is here! Let's dive into the details.

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The Gory Details: Outlook Search Glitch​

It all started around January 16, 2025, when users reported that Outlook 2016 (MSI version) stopped properly displaying the sender’s name in search results. Imagine searching your inbox for an urgent email and all you see in the "From" column of the results are blank fields. That’s not just frustrating—that’s downright debilitating if you rely on Outlook for work.
What's worse, these botched search results appear as if they’re unread emails, further confusing users and possibly leading to unnecessary panic. If this rings a bell and you’re a Microsoft 365 (M365) administrator, you may have caught this issue being tracked under ID MC976059 on the M365 Service Health dashboard. Yes, that’s the same ID Microsoft recently recycled for another bug. At this point, even bug IDs feel like déjà vu.
The blame? Microsoft hints at a recent code change on their back end affecting the Exchange Server-assisted search function. Basically, the mechanism Outlook uses to search your emails on the server side has gone rogue, leading to these mangled results.

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Workaround: The Registry Editor Saves the Day​

If you’re not keen on waiting for Microsoft to roll out a global fix (and who is?), there’s a temporary Registry tweak that disables the flawed server search functionality. Instead, Outlook will fall back on the good ol’ Windows Desktop Search—it’s like ditching GPS and grabbing a paper map. Here’s how you can apply the workaround:

• Open the Registry Editor (type regedit.exe in the Start Menu).
• Navigate to:
  

     HKEY_CURRENT_USER\software\policies\Microsoft\office\16.0\outlook\search

• Look for—or create, if it doesn’t exist—a DWORD named DisableServerAssistedSearch.
• Set its value to 1. This disables the server search and switches Outlook to its local search capabilities.
• Close the Registry Editor and restart Outlook.

Congratulations! By sacrificing server-assisted search, you should be able to view your sender details and stop false unread statuses from haunting your inbox.
Important Note: Cranking up the Registry Editor is not for the faint of heart. Even a tiny typo in the wrong location could disrupt your entire system. If you’re unsure, recruit your company’s IT guru or administrator to handle this safely.

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What’s Next? The Hunt for a Permanent Fix​

Microsoft’s service team isn’t snoozing. They’ve acknowledged the issue and are working on rolling back the changes that sparked this ruckus in the first place. Currently, they’re testing the rollback internally before deploying the fix across environments.
Translation: there’s hope for a permanent solution, but patience will be key.

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What is Exchange Server-Assisted Search Anyway?​

For the uninitiated, let’s briefly talk about Server-assisted Search in Outlook. When you search your inbox in Outlook, there are two main strategies at play:

• Windows Desktop Search: This relies on your local machine to index emails stored on your computer. It's fast, reliable (mostly), but limited to what’s cached locally.
• Server-assisted Search: This reaches out to your email server (think Microsoft Exchange servers or Office 365) to pull search results in real time. This comes in handy if you have a gigantic mailbox and don’t cache all emails locally.

The benefit of server-assisted search is its ability to comb through every nook of your mailbox, even emails stored far back in your archives or messages you haven’t downloaded. However, as we’ve seen, reliance on the server can become a problem when things go pear-shaped, as they have here.

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Broader Implications for IT Pros and Businesses​

For IT administrators managing environments with legacy software like Outlook 2016, this latest snafu highlights an ongoing trade-off between stability, feature deprecation, and Microsoft's relentless updates. Sure, Microsoft still supports older Office suites to a degree, but the frequency of weird bugs with legacy versions seems to be increasing as Redmond works to push more users into newer, subscription-based editions like Microsoft 365.
So, should you consider upgrading?

• If you're stuck with Outlook 2016 due to licensing costs or compatibility issues, this workaround will let you limp along until Microsoft issues a fix. However, it’s worth noting that this is yet another reminder that older software isn’t immune to bugs.
• For organizations, this may be a wake-up call to evaluate whether clinging to aging Outlook versions is worth the risks. If your workforce depends heavily on email (whose doesn’t?), it might be more cost-effective in the long run to move to an actively supported version of Office.

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Final Thoughts: Fixing Search is Lipstick on a Pig​

This isn’t Microsoft’s first rodeo with Outlook search issues, and it probably won’t be the last. Whether it’s Exchange-based searches misbehaving or local indexing throwing tantrums, search reliability has always been Outlook’s Achilles’ heel.
For now, the ball is in Microsoft’s court to roll out a fix pronto. In the meantime, if you’re one of the affected users, make the Registry tweak and carry on. And don’t forget—if you’ve implemented this fix, keep an eye on updates or advisories from Microsoft to know when it’s safe to revert.
Have you encountered this bug yet? Did you apply the workaround, or are you waiting for Microsoft’s permanent solution? Let us know your thoughts in the forum—let’s troubleshoot together!

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Source: Neowin Microsoft offers Registry workaround for broken Outlook 2016 Search