Spell check is on by default in Outlook, but you may need to adjust settings if it's not working

Outlook has spell check built in and running automatically for most users. When you type an email, misspelled words appear with a red underline. However, if you don't see those red lines, or if spell check stopped working, the feature may be turned off in your settings or disabled for your language. The steps to turn it back on depend on whether you use Outlook on the web, Outlook desktop for Windows, or Outlook for Mac.

Spell check in Outlook works only in the message body and subject line — it does not check recipient names or addresses. It also uses the language you've set in your Outlook preferences, so if you write in multiple languages, you may need to add additional dictionaries or change your default language setting.

Key Takeaways

  • Spell check is enabled by default in Outlook, but you can turn it on or off in Settings under Mail or Preferences depending on your version.
  • In Outlook on the web, go to Settings > Mail > Compose and reply, then toggle "Use spelling checker" to on.
  • In Outlook desktop for Windows, go to File > Options > Mail > Spelling, then check "Always suggest replacements for misspelled words."
  • In Outlook for Mac, go to Outlook > Preferences > Spelling and Grammar, then check "Check spelling while you type."
  • If spell check is on but not working, your language setting may be wrong, or you may need to add a new language to your dictionary.

Turning on spell check in Outlook on the web

If you use Outlook through a web browser (outlook.office.com or outlook.live.com), spell check is usually on by default. To confirm it's enabled, click the gear icon in the top right corner and select "View all Outlook settings."

In the settings menu, click "Mail" in the left sidebar, then find "Compose and reply." Look for the toggle labeled "Use spelling checker" and make sure it is switched to the on position. If it's already on and you still don't see red underlines under misspelled words, scroll down in the same section and check that your language is set correctly — spell check only works in the language you've selected.

Once you've made changes, click "Save" at the bottom of the page. You don't need to close and reopen Outlook; the change takes effect immediately.

Turning on spell check in Outlook desktop for Windows

In Outlook for Windows, spell check is on by default, but you can verify and adjust it through the Options menu. Click "File" in the top left, then select "Options."

In the Options window, click "Mail" in the left sidebar. Scroll down until you see the "Spelling" section. Check the box next to "Always suggest replacements for misspelled words" if it is not already checked. You can also check "Ignore words in UPPERCASE" and "Ignore words with numbers" if you want spell check to skip those types of words.

Below the spelling options, you'll see "Editor Options." Click that button to access more detailed settings, including whether to check spelling as you type or only when you send. Once you've made your changes, click "OK" to save and close the Options window.

Turning on spell check in Outlook for Mac

On a Mac, open Outlook and click "Outlook" in the menu bar at the very top of the screen. Select "Preferences" from the dropdown menu.

In the Preferences window, find and click "Spelling and Grammar." Check the box next to "Check spelling while you type." You can also choose which language Outlook uses for spell check by selecting it from the "Language" dropdown. If you write in multiple languages, you may want to select "Automatic by language" so Outlook detects the language as you type.

Close the Preferences window when you're done. The changes take effect immediately in any new emails you compose.

What to do if spell check is on but not working

If you've turned on spell check and still don't see red underlines under misspelled words, the problem is usually a language mismatch. Spell check only works in the language you've set as your default. If you write in English but your Outlook language is set to Spanish, for example, spell check won't catch English mistakes.

Check your language setting in your Outlook preferences or settings. In Outlook on the web, this is in Settings > Mail > Compose and reply. In Outlook for Windows, go to File > Options > Language. In Outlook for Mac, go to Outlook > Preferences > Spelling and Grammar. Make sure the language matches the language you're writing in.

If you write in multiple languages regularly, some versions of Outlook allow you to add multiple languages to your dictionary. In Outlook for Windows, you can do this by going to File > Options > Proofing > Dictionaries. In Outlook on the web and Mac, you may need to change the language setting each time you switch languages, or use the automatic language detection option if available.

Understanding Outlook's spell check limitations

Outlook's spell check has some built-in limits. It checks only the message body and subject line — it will not flag misspelled names in the "To," "Cc," or "Bcc" fields. It also does not check the names of attachments or any text inside attached files.

Spell check in Outlook uses a standard dictionary, so it may not recognize proper nouns, technical terms, or words specific to your industry. If you find yourself adding the same word repeatedly and want Outlook to stop flagging it, you can right-click the underlined word and select "Add to Dictionary." That word will then be recognized in all future emails.

Some versions of Outlook also include grammar checking alongside spell check. If you have grammar checking enabled, you'll see blue underlines for grammar issues in addition to red underlines for spelling. Grammar checking is separate from spell check and may need to be turned on in a different settings section.

Frequently Asked Questions

Why does spell check work in some emails but not others?

This usually happens when you change the language setting mid-email or when you paste text from another source that has a different language tag. Try selecting all the text in your message (Ctrl+A on Windows, Command+A on Mac), then right-click and set the language to your default. Spell check should then work across the entire message.

Can I turn off spell check for just one email?

Not directly in Outlook itself. However, you can disable spell check globally in your settings, write the email, then turn it back on. In most versions, you can also right-click a flagged word and select "Ignore All" to stop Outlook from flagging that word in that specific email.

Does Outlook spell check work in the subject line?

Yes. Spell check in Outlook covers both the subject line and the message body. If you see a red underline in your subject, it means Outlook has flagged a potential misspelling there.

What's the difference between spell check and grammar check in Outlook?

Spell check catches misspelled words (red underlines). Grammar check catches sentence structure, punctuation, and word choice issues (blue underlines). They are separate features, and you can turn one on while the other is off. Grammar check is not available in all versions of Outlook.