How to Turn On Spell Check in Outlook (And Why It Might Not Be Working)
Spell check in Outlook is one of those features most people assume is always on — until they send an email with a typo and realize it wasn't. Whether you're setting it up for the first time, troubleshooting why it stopped working, or customizing how it behaves, the process varies depending on your version of Outlook and how your system is configured.
What Spell Check in Outlook Actually Does
Outlook's spell check works in two distinct ways: automatic spell check (the red squiggly underline that appears as you type) and manual spell check (triggered before you send or on demand with F7). Both can be enabled or disabled independently, and both pull from the same underlying proofing engine that Microsoft Office uses across Word, PowerPoint, and other apps.
This shared engine is important to understand. If spell check is broken in Outlook, it's often broken across Office — and the fix usually lives at the Office level, not just inside Outlook.
How to Enable Spell Check in Outlook (Step by Step)
In Outlook for Windows (Microsoft 365 / Outlook 2016, 2019, 2021)
- Open Outlook and go to File → Options
- Select Mail from the left-hand menu
- Scroll to the Compose messages section
- Check "Always check spelling before sending" to enable the pre-send check
- Click OK
To enable the automatic underline-as-you-type feature:
- Go to File → Options → Mail
- Click the "Spelling and Autocorrect…" button
- In the Editor Options window, select Proofing
- Under "When correcting spelling in Outlook", check "Check spelling as you type"
- Click OK
In Outlook on the Web (Outlook.com / Microsoft 365 Web)
The web version of Outlook relies on your browser's built-in spell check rather than an Office proofing engine. To enable it:
- Chrome: Settings → Advanced → Languages → toggle on "Check spelling"
- Edge: Settings → Languages → toggle on "Use spell check"
- Firefox: Right-click any text field → "Check Spelling"
There is no standalone spell check setting inside Outlook on the web itself — the browser handles it entirely.
In the New Outlook for Windows (2023 and later)
Microsoft has been rolling out a redesigned Outlook experience. In the new Outlook, the proofing settings are accessed through:
- Settings (gear icon) → General → Language and time
- Or through Settings → Mail → Compose and reply
The exact menu layout can differ based on which build you're running, since Microsoft has been updating the interface in stages.
In Outlook for Mac
- Open Outlook and go to Outlook → Preferences
- Click Spelling and Grammar (or Autocorrect in some versions)
- Toggle on "Check spelling as you type"
- Optionally enable "Check grammar with spelling"
macOS also has a system-level spell check under System Settings → Keyboard → Text Input, which can interact with Outlook's behavior.
Common Reasons Spell Check Stops Working 🔍
Even after enabling it, spell check sometimes fails silently. These are the most frequent causes:
| Issue | What's Happening | Where to Fix It |
|---|---|---|
| Wrong proofing language | Outlook is checking against a different dictionary | File → Options → Language |
| "Do not check spelling" flag | Text is marked to skip proofing | Select all text → Review → Language → uncheck "Do not check spelling" |
| Corrupt Office installation | The proofing tools weren't installed or got corrupted | Control Panel → Repair Office |
| Spell check disabled in Word | Outlook uses Word as its editor in some setups | Word Options → Proofing |
| Custom dictionary conflicts | User dictionary is interfering | File → Options → Proofing → Custom Dictionaries |
One specific issue worth noting: text pasted from external sources often carries a "do not check spelling" attribute. If only certain emails have no spell check, this is usually why.
The Language Setting Variable
Outlook's proofing engine must be set to a language that has a proofing pack installed. If you've set your display language to one language but your proofing language to another — or if Office was installed without proofing tools for your language — spell check will appear to do nothing.
You can verify this by going to File → Options → Language and checking which language is set as the default for proofing. If it shows "proofing not available," you'll need to install the relevant Language Accessory Pack from Microsoft.
How Your Outlook Version Changes the Picture ✉️
The steps above cover the main configurations, but what works on one setup may not apply to another. The classic desktop Outlook, the new Outlook for Windows, Outlook for Mac, and Outlook on the web are functionally different applications that happen to share a name. They handle proofing differently, store settings differently, and receive updates on different schedules.
Users on Microsoft 365 subscriptions are also more likely to be running the newest version — which may have menu layouts that look slightly different from what's documented in older guides. If a menu item isn't where you expect it, searching "spelling" inside the Options or Settings search bar usually gets you there directly.
Whether the built-in options are enough — or whether you'd benefit from a third-party grammar tool layered on top — depends on how much you rely on email for professional communication, how often you're composing from different devices, and how much control you want over the proofing behavior. Your own workflow is the part only you can evaluate.