How to Turn On Spell Check in Outlook (And Make Sure It Actually Works)
Spell check in Outlook is one of those features that should just work — but depending on your version, settings, or even how you installed Office, it can behave differently from one machine to the next. Here's a clear breakdown of how it works, where the settings live, and what variables affect whether you're getting reliable spell checking.
What Spell Check in Outlook Actually Does
Outlook's spell check isn't a standalone engine — it's powered by the same proofing tools used across Microsoft Office (Word, PowerPoint, Excel). This means when you enable or configure spell check in Outlook, you're often adjusting settings shared across the entire Office suite.
There are two distinct layers to how spell check works in Outlook:
- Automatic spell check — underlines misspelled words in red as you type
- Check before send — reviews your message for errors automatically when you hit Send
Both can be enabled independently, and both have their own quirks depending on your setup.
Where to Find Spell Check Settings in Outlook
In Outlook for Windows (Microsoft 365 / Office 2016–2021)
- Open Outlook and go to File → Options
- Click Mail in the left sidebar
- Scroll to the Compose messages section
- Check the box for "Always check spelling before sending"
To enable real-time spell checking (red underlines as you type):
- Still in File → Options, click Mail
- Click the "Spelling and Autocorrect…" button
- Go to Proofing
- Make sure "Check spelling as you type" is checked under When correcting spelling in Outlook
In Outlook on the Web (Outlook.com / Microsoft 365 Web App)
Outlook on the web relies heavily on your browser's built-in spell checker rather than Office's proofing engine. This means:
- In Chrome or Edge, spell checking is handled at the browser level — right-click a misspelled word to see suggestions
- You can enable browser spell check in Chrome via Settings → Advanced → Languages
- Microsoft 365 web does offer some light in-app checking, but it's less robust than the desktop version
In the New Outlook for Windows
Microsoft has been rolling out a redesigned Outlook app that more closely mirrors Outlook on the Web. In this version:
- Click the Settings gear (top right)
- Go to General → Accessibility or search "spell check" in the settings search bar
- Toggle on spell checking options as available
The new Outlook's spell check behavior may differ from classic Outlook desktop — this is one of the more common sources of confusion as users are migrated between versions.
In Outlook for Mac
- Open a new message
- Go to Edit → Spelling and Grammar
- Select "Check Spelling While Typing"
Alternatively, go to Outlook → Preferences → Spelling and Grammar for full control over proofing options.
Why Spell Check Might Not Be Working 🔍
Even after enabling the setting, spell check sometimes fails silently. Common reasons include:
| Issue | Likely Cause |
|---|---|
| No red underlines in compose window | "Check spelling as you type" is off |
| Spell check skips certain text | Text formatted as a different language |
| Spell check works in Word but not Outlook | Outlook-specific proofing setting is disabled |
| Feature greyed out or missing | Office installation may be missing proofing language packs |
| Spell check ignores signature or quoted text | By design — Outlook skips those regions |
The Language Setting Problem
One particularly sneaky issue: if the proofing language on a block of text is set incorrectly (e.g., set to French when you're typing in English), spell check will either flag everything or flag nothing — depending on whether that language pack is installed.
To fix this in desktop Outlook: select your message text → go to Review → Language → Set Proofing Language and confirm it matches what you're writing in.
AutoCorrect vs. Spell Check — Not the Same Thing
It's worth separating these two features since they're often confused:
- Spell check identifies errors and suggests corrections — reactive
- AutoCorrect automatically fixes common typos as you type — proactive
Both live under File → Options → Mail → Spelling and AutoCorrect, but they serve different roles. You can have one on without the other, which sometimes explains why words are being "fixed" without red underlines, or vice versa.
Variables That Affect Your Experience ⚙️
How well spell check works in Outlook depends on factors specific to your environment:
- Outlook version — classic desktop, new Outlook, web app, and Mac all behave differently
- Office installation type — volume license, Microsoft 365 subscription, or standalone may have different proofing tool availability
- Language packs installed — spell check only works for languages with installed dictionaries
- IT/admin policies — in corporate environments, some settings may be locked or managed centrally
- Operating system — macOS and Windows handle the Office proofing integration differently
- Whether you're using the HTML, Plain Text, or Rich Text compose format — some formatting modes interact differently with proofing tools
For most personal and home users, enabling the two core settings (check as you type + check before send) covers the majority of needs. But for users in managed enterprise environments, shared devices, or multilingual workflows, the right configuration looks meaningfully different — and may require changes your IT department needs to make rather than anything accessible in your personal settings. 🖥️