How to Clear Cache in Outlook

Microsoft Outlook is one of the most widely used email and scheduling platforms worldwide. From managing your inbox to keeping track of appointments, it’s a powerful tool for professionals and casual users alike. However, over time, Outlook can slow down, behave erratically, or show outdated content. One of the most common fixes to many of these issues is clearing the cache.

TL;DR:

Clearing the cache in Outlook can help resolve slow performance, incorrect autocomplete suggestions, or outdated email content. The cache stores temporary files that speed up your experience, but when corrupted, they can cause issues. You can clear cache data including autocomplete entries and OST files depending on the problem. Just a few simple steps can make Outlook run smoother and faster.

What is Cache in Outlook?

Before jumping into the “how,” let’s understand what we’re dealing with. In Outlook, the cache is a collection of temporary files that help Outlook operate more efficiently. These files might include:

• Autocomplete email addresses
• Cached Exchange Mode data (local copies of your mailbox)
• Temporary attachments and calendar data

Over time, these files can become outdated or corrupted, making Outlook behave unusually. This could mean anything from an email not showing up properly to a sluggish interface.

When Should You Clear Outlook’s Cache?

Here are some signs that it’s time to clear your Outlook cache:

• Outlook is running slowly or freezing
• You’re not seeing updated emails or calendar events
• Autocomplete is suggesting wrong or outdated entries
• Emails are stuck in Outbox or Drafts
• You’re getting frequent sync errors

Clearing the cache can act as a hard reset and often resolves these pressing issues quickly.

Different Types of Outlook Cache & How to Clear Them

1. Clear Autocomplete Cache

This is the cache that stores email addresses you’ve previously typed. If you’re being shown incorrect or outdated suggestions, here’s how to clear this:

1. Open Outlook.
2. Click on File → Options.
3. Navigate to Mail.
4. Scroll down to the Send messages section.
5. Click on Empty Auto-Complete List.

This will clear the list of previously used email addresses. Don’t worry, Outlook will begin to build the list again as you send new emails.

2. Clear Outlook Cache Folder (Temporary Files)

Outlook stores a wide range of temporary items in a dedicated cache folder. Here’s how to manually delete those files:

1. Close Outlook completely.
2. Press Windows + R to open the Run dialog box.
3. Type %localappdata%\Microsoft\Outlook and hit Enter.
4. This will open a folder that contains files known as the OST files or Cached Exchange files.
5. Select the contents and delete them, or move them to a backup folder if you’re cautious.

When you reopen Outlook, it will begin to recreate the necessary cache files automatically.

3. Delete and Rebuild OST File

The Offline Storage Table (OST) file is a local copy of your mailbox data. Sometimes, it can become corrupted. Here’s how to regenerate it:

1. Close Outlook.
2. Navigate again to %localappdata%\Microsoft\Outlook using Windows Run.
3. Find the OST file associated with your email account and delete it.
4. Reopen Outlook. It will connect to the mail server and rebuild the OST file automatically.

This can fix synchronization problems and missing items in your mailbox.

Clear Outlook Cache in Web Version (Outlook Web App)

Although the cache issue is more common in desktop Outlook, if you’re using Outlook Web App (OWA), your browser cache might affect its performance. Here’s how to address that:

For Chrome:

1. Click the three-dot menu on the top-right corner.
2. Select More tools → Clear browsing data.
3. Select Cookies and other site data and Cached images and files.
4. Click Clear data.

For Firefox or Edge:

• Go to Settings → Privacy & Security
• Find the cache and cookie settings
• Clear the cache specific to the outlook website, if possible

This will solve problems like login issues or slow-loading inbox in OWA.

Bonus Tip: Use Outlook in Safe Mode

If you’re not sure whether an add-in is causing a cache buildup or Outlook is becoming unstable, you can run Outlook in Safe Mode to isolate the issue:

1. Press Windows + R.
2. Type outlook.exe /safe and press Enter.

This launches Outlook without any third-party add-ins, helping clean up cached plugins or configurations that may be problematic.

What to Know Before Clearing Cache

Although clearing cache is generally safe, there are a few things to keep in mind:

• Your first launch of Outlook after clearing cache may be slower as data is rebuilt
• Autocomplete suggestions will initially disappear
• You may need to re-login or confirm account settings depending on the cache cleared

How Often Should You Do This?

There’s no fixed schedule, but a good guideline is to clear the Outlook cache:

• Every 3 to 6 months
• When you switch computers or reinstall Outlook
• Whenever you notice persistent issues

It’s also good hygiene if you’re using Outlook in a shared or working environment with fluctuating data loads.

Automated Tools vs Manual Clearing

Some third-party software, like CCleaner or Outlook-specific utilities, can automate this process. However, manual clearing gives you more control, especially if you’re dealing with specific issues like OST corruption or autocomplete problems.

Conclusion

Clearing the cache in Outlook isn’t just tech wizardry—it’s digital spring cleaning. Whether you’re a daily user or the go-to tech support for your office, understanding how and when to clear Outlook’s cache can keep your productivity flowing and your email running silky smooth.

So, the next time Outlook throws a tantrum, you now have a powerful trick up your sleeve: just clear the cache!