How to Turn on Spell Check in Outlook (2026 Guide)

We’ve all been there. You hit “Send” on a crucial client email, take a sip of coffee, and then spot it—a glaring typo in the subject line. Your stomach drops. You quickly check if they’ve replied with an awkward “I guess I’ll just leave it,” but the silence is worse. In those moments, you’re left wondering why your trusty spell checker stayed silent.

If you’ve recently faced this frustration, you aren’t alone. It’s a surprisingly common issue that often stems from a simple setting toggle rather than a broken application. The problem is that Outlook spell check isn’t a single, unified feature anymore; it behaves differently depending on whether you are using New Outlook, the Classic Desktop app, or the Web version.

In this guide, I’ll walk you through exactly how to turn on spell check in Outlook across all three major platforms. We’ll also dive into why that elusive red squiggly line might have disappeared and how to get it—and your confidence—back.

How to Turn on Spell Check in Outlook (New vs. Classic vs. Web)

One of the biggest sources of confusion in the IT support world is the fragmented interface of Outlook. What worked in 2019 doesn’t always work in 2026. Let’s break down the specific steps for each version.

Enabling Spell Check in New Outlook for Windows

Microsoft’s push toward "New Outlook" (the web-based wrapper) has shifted how settings are managed. The old File > Options menu is largely gone here. Instead, Microsoft has consolidated proofing tools into a centralized Editor experience, particularly for Microsoft 365 subscribers.

To ensure your spell checker is active:

1. Click the gear icon (Settings) in the top-right corner.
2. Navigate to Mail > Compose and reply.
3. Look for the section labeled Editor.
4. Toggle on Check spelling as you type.

Note for M365 Users: If you subscribe to Microsoft 365, you likely have access to the Editor pane. This is a more robust tool that checks not just spelling but also clarity, conciseness, and tone. You can access it by clicking the "Editor" button in the new email ribbon. It’s worth exploring, as it catches nuances that the basic spell checker misses.

Enabling Spell Check in Classic Outlook (Desktop)

For users who prefer the traditional, feature-rich desktop experience (or those still on Outlook 2019/2021), the settings are tucked away in the classic options menu.

On Windows:

1. Go to File > Options.
2. Select Mail from the left sidebar.
3. Click the Spelling and Autocorrect... button.
4. Ensure the box for Check spelling as you type is checked.
5. Click OK to save.

On Mac: The path is slightly different. Go to Outlook in the top menu bar, select Settings (or Preferences), then click Spelling and Grammar. Here, you can verify that automatic checking is enabled.

It’s important to distinguish these paths because toggling the setting in New Outlook won’t affect Classic, and vice versa. They maintain separate configuration states.

Configuring Outlook Web App (Outlook.com/M365)

If you’re accessing your email via a browser at Outlook.com or the OWA portal, the interface relies heavily on browser capabilities combined with Microsoft’s web settings.

1. Click the gear icon in the top-right corner.
2. Go to General > Editor.
3. Here you will find toggles for spell check and grammar check.
4. Ensure the relevant switches are turned on.

Comparison Note: The Web UI is cleaner but sometimes less granular than the desktop app. For instance, managing custom dictionaries is easier in the desktop versions. If you find the web version is missing a feature you need, consider switching to the desktop client for heavy drafting, or simply use the browser’s built-in spell check (like Chrome’s or Edge’s) as a backup.

Outlook Spell Check Not Working? 5 Deep Troubleshooting Fixes

If you’ve verified your settings and the red squiggly lines still refuse to appear, the issue is likely deeper than a simple toggle. Over my 15 years in IT support, I’ve found that when users report broken spell check, it’s rarely the software being "broken" in the traditional sense. It’s usually a conflict or a corrupted state.

Here are the five most effective fixes, ranked from easiest to most involved.

Fix 1: Reset Ignored Words and Grammar

This is the number one culprit I see. Over time, you may have accidentally clicked "Ignore All" on a common word, or your ignored-words list has become bloated with technical jargon or names that are now incorrect. When the ignore list is full or contains conflicts, the spell checker can sometimes stop flagging new errors entirely.

How to fix it:

1. Go to File > Options > Proofing (in Classic Outlook).
2. Look for the Recheck Document button.
3. Click it and confirm the warning.

This clears the temporary ignore list for your current session, forcing Outlook to re-evaluate every word against the dictionary. If you are on Mac, go to Tools > Spelling and Grammar > Reset Ignored Words and Grammar.

Fix 2: Check Default Language Settings

Spell check is language-specific. If your system language is set to French but your email is in English, Outlook might behave erratically. Conversely, if you recently traveled or changed your region settings, your default proofing language might have switched.

How to fix it:

1. In the Spelling and Autocorrect dialog, click Language.
2. Ensure your primary language (e.g., English (United States)) is selected as the default.
3. Make sure the box Do not check spelling or grammar is unchecked for your primary language.

Example: I once helped a colleague who couldn’t understand why "color" was flagged as an error. His default language had silently switched to British English, which doesn’t flag it, but his custom dictionary was a mix of US and UK terms, causing a conflict that disabled checking for that specific document.

Fix 3: Disable Add-ins Conflicting with Proofing

Third-party plugins are a double-edged sword. While tools like Grammarly, Hemingway, or custom VSTO add-ins are helpful, they can sometimes override Outlook’s native proofing engine. If an add-in hooks into the text input stream incorrectly, it can suppress the red underlines.

How to test this: Run Outlook in Safe Mode. This disables all add-ins.

1. Press Win + R, type outlook /safe, and hit Enter.
2. Try typing a sentence with a deliberate typo.

If the spell checker works in Safe Mode, one of your add-ins is the problem. Go to File > Options > Add-ins, click Go next to COM Add-ins, and disable them one by one to find the offender.

Fix 4: Repair Microsoft Office Installation

If your proofing tools are corrupted—perhaps due to a failed update or a bad registry key—you may need to repair the Office suite itself. This is a nuclear option, but it’s effective when nothing else works.

How to fix it:

1. Go to Control Panel > Programs and Features (or Settings > Apps).
2. Find Microsoft Office (or Microsoft 365) in the list.
3. Select it and click Change.
4. Choose Quick Repair first. This runs offline and usually fixes DLL corruption related to proofing tools.
5. If Quick Repair fails, try Online Repair, which is more thorough but takes longer.

Fix 5: Mobile Outlook App Settings (iOS/Android)

Spell checking on mobile is a different beast entirely. The Outlook mobile app often relies on the device’s system-level keyboard rather than its own internal proofing engine.

How to fix it:

• iOS: Go to Settings > General > Keyboard and ensure Check Spelling is toggled on. Also, check if you’re using a third-party keyboard like Gboard or SwiftKey, as their individual settings might override system defaults.
• Android: Go to Settings > System > Languages & input > On-screen keyboard > Gboard (or your default) > Correct text > Show correction suggestions.

If spell check is failing on mobile, the issue is almost always at the OS keyboard level, not within the Outlook app itself.

Customize Your Outlook Spell Check: Language, Dictionary, and Shortcuts

Once your spell checker is working, you might want to fine-tune it. After all, your profession likely has its own jargon that no standard dictionary knows.

Adding Custom Words to the Outlook Dictionary

Did you just get flagged for a client acronym or a proper name? Instead of clicking "Ignore" every time, add it permanently.

1. Right-click the word with the red underline.
2. Select Add to Dictionary.

Pro Tip: The custom dictionary file is stored locally on your machine. On Windows, it’s typically located at %APPDATA%\Microsoft\Proof. If you’re migrating to a new PC, remember to back up this file if you have a long list of specialized terms.

Changing Proofing Languages for Multilingual Emails

If you write emails in multiple languages, you don’t need to switch your entire system language. Outlook allows you to assign different proofing languages to different parts of your text.

1. Highlight the text in the foreign language.
2. Go to Review > Language > Set Proofing Language.
3. Select the appropriate language (e.g., Spanish) and ensure "Do not check spelling or grammar" is unchecked.

This is incredibly useful for bilingual professionals. It prevents the spell checker from flagging valid Spanish words while you’re drafting an English email.

Essential Keyboard Shortcuts for Spell Checking

Speed matters. Here are the shortcuts that will make you look like a power user:

Turn On Grammar Check in Outlook: Beyond Spelling

Spelling is about correctness; grammar is about clarity. And in professional communication, clarity is king.

Difference Between Spell Check and Grammar Check

It’s easy to confuse the two, but they serve different purposes.

• Spell Check: Uses a dictionary. If "teh" is in the dictionary, it won’t be flagged. If "the" is misspelled as "thee," it will be. It’s marked with a red squiggly line.
• Grammar Check: Uses rules and algorithms. It looks for subject-verb agreement, punctuation errors, and sentence structure. It’s marked with a blue squiggly line on Windows and a green squiggly line on Mac.

Why limited availability? Grammar checking is computationally expensive. That’s why it’s only available in Word, PowerPoint, and Outlook—the apps where long-form prose is common. You won’t find it in Excel or Access.

How to Enable Grammar Checking in Outlook Desktop

Grammar check is often disabled by default in older versions of Outlook to improve performance.

In Classic Outlook:

1. Go to File > Options > Mail > Spelling and Autocorrect.
2. Check the box for Mark grammar errors as you type.
3. Also ensure Check grammar with spelling is checked if you want integrated checking.

In New Outlook / Microsoft 365: Use the Editor pane mentioned earlier. It offers much more sophisticated grammar suggestions, including style and tone improvements. It’s essentially a mini-Grammarly built into Outlook. If you care about how your email sounds, not just how it’s spelled, spend some time exploring the Editor pane.

FAQ

How do I turn on automatic spell checking in New Outlook? Go to the gear icon (Settings) > Mail > Compose and reply. Under the Editor section, toggle on "Check spelling as you type."

Why is my Outlook spell check not working anymore? The top three causes are: 1) A bloated ignored-words list, 2) Incorrect default language settings, and 3) A conflicting third-party add-in. Try resetting the ignored words list first.

How do I disable spell check in Outlook email? Go to File > Options > Mail > Spelling and Autocorrect, and uncheck "Check spelling as you type." This will stop the red underlines, but you can still run a manual check with F7.

What is the shortcut for spell check in Outlook? Press F7 to run the spell check. Use Alt + F7 to jump directly to the next error.

How do I add a word to the Outlook dictionary? Right-click the misspelled word and select "Add to Dictionary." It will be remembered in future sessions.

Conclusion

Getting your outlook spell check to work properly shouldn’t be a hurdle, but with the fragmentation between New, Classic, and Web versions, it’s easy to get lost in the settings.

The key takeaway is that most "broken" spell checkers are simply misconfigured. By checking your version-specific settings, clearing your ignored words, and ensuring your language preferences match your content, you can restore that vital safety net. Don’t forget to leverage the Editor pane in Microsoft 365 for grammar—that’s where the real writing assistance lives.

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