Spell check is on by default in Outlook, but you may need to turn it back on if it stopped working

Outlook checks your spelling as you type in the message body — red squiggles appear under misspelled words. If you do not see those squiggles, spell check is either turned off or set to check only when you send. The steps to turn it back on depend on which version of Outlook you use and whether you are working on Windows, Mac, or the web.

The fastest way to know which version you have: open Outlook and look at the top left corner. If it says "Outlook" with a version number (like "Outlook 2024" or "Outlook 2021"), you have the desktop version. If the window says "Outlook on the web" or you are using Outlook in a browser, follow the web steps below.

Key Takeaways

  • Outlook for Windows and Mac check spelling by default as you type, but you can turn this off in settings and turn it back on the same way.
  • In Outlook on the web, spell check runs only when you send a message unless you manually check it first.
  • If spell check is on but not showing red squiggles, the language setting may be wrong or the dictionary may need to be reset.
  • Right-clicking a red squiggle lets you accept a suggestion, ignore the word, or add it to your personal dictionary so Outlook stops flagging it.
  • Spell check does not catch grammar mistakes, only misspelled words — use a separate tool if you need grammar checking.

Turn on spell check in Outlook for Windows

Open Outlook and go to File in the top left. Click Options (near the bottom of the menu). In the Options window, click Mail on the left side.

Scroll down until you see Spelling. You should see a checkbox next to "Check spelling as you type". If it is unchecked, click it to turn spell check on. Then click OK at the bottom of the window. Spell check will start working the next time you open a new message.

If you see the checkbox is already checked but spell check is still not working, try unchecking it, clicking OK, then going back to File > Options > Mail and checking it again. This resets the spell check engine.

Turn on spell check in Outlook for Mac

Open Outlook and click Outlook in the menu bar at the very top of the screen. Click Preferences. In the Preferences window, look for Spelling (you may need to scroll or search for it).

Make sure the checkbox next to "Check spelling as you type" is checked. If it is not, click it. Then close the Preferences window. Spell check will work in your next new message.

On Mac, spell check uses the system dictionary, which is shared across all applications. If spell check is on but not working, go back to Preferences > Spelling and click Reset if that button appears. This clears any corrupted dictionary data.

Turn on spell check in Outlook on the web

Outlook on the web does not check spelling as you type. Instead, it checks only when you send. To check spelling before you send, click the three dots (more options) in the message toolbar and look for Editor Options or Spelling. Click it to see any flagged words.

If you want Outlook on the web to check spelling automatically before sending, this setting is not available in the web version. The desktop version of Outlook (Windows or Mac) is the only one that checks as you type.

Fix spell check when it is on but not showing red squiggles

If spell check is turned on and you still do not see red squiggles under misspelled words, the language setting may be wrong. Open a new message and look at the bottom of the compose window. You should see a language listed (usually "English (United States)" or similar). Click it and make sure it matches the language you are writing in.

If the language is correct but spell check still is not working, the dictionary file may be corrupted. In Outlook for Windows, go to File > Options > Mail > Spelling and click Custom Dictionaries. Look for a dictionary file with your language name. Click it and then click Delete. Outlook will create a new one the next time you compose a message.

On Mac, the dictionary is part of the system, so you cannot delete it from Outlook. Instead, restart your computer. This usually clears any corrupted dictionary data.

What to do when Outlook flags a word that is spelled correctly

Right-click (or Control-click on Mac) the red squiggle. A menu will appear with options. Click Add to Dictionary to tell Outlook that word is correct. Outlook will stop flagging it from that point on.

If you want Outlook to stop flagging a word just in this one message, click Ignore All instead. The word will still be flagged in future messages, but not in this one. This is useful for proper names, technical terms, or words that are correct in context but not in a standard dictionary.

Spell check versus grammar check — what each one does

Spell check catches misspelled words only. It does not catch grammar mistakes, missing words, or awkward phrasing. Outlook does not have a built-in grammar checker. If you need grammar checking, you can install the Microsoft Editor add-in, which is free and works in Outlook, Word, and the web.

To add Microsoft Editor to Outlook for Windows, go to File > Get Add-ins > Search for "Editor" > Install. On Mac, go to Insert > Get Add-ins > Search for "Editor" > Install. Once installed, Editor will underline grammar and style issues in blue and offer suggestions when you click them.

Frequently Asked Questions

Why does Outlook spell check only when I send, not as I type?

You are likely using Outlook on the web, which does not have a "check as you type" option. The desktop versions of Outlook (Windows and Mac) check as you type by default. If you are using desktop Outlook and it is only checking at send time, go to File > Options > Mail and make sure "Check spelling as you type" is checked.

Can I add a word to Outlook's dictionary so it stops flagging it?

Yes. Right-click the red squiggle and click Add to Dictionary. That word will no longer be flagged in any message you write. If you change your mind later, there is no straightforward way to remove it from the dictionary in Outlook itself, but you can do it through Windows settings or Mac system preferences if you need to.

Does spell check work in Outlook on my phone?

Outlook on iPhone and Android does not have a dedicated spell check feature. Instead, it uses your phone's built-in spell check, which works the same way as in any other app — red squiggles appear as you type, and you can tap them to see suggestions. The behavior depends on your phone's settings, not Outlook's.

What languages does Outlook spell check support?

Outlook supports spell check in dozens of languages, including English, Spanish, French, German, Chinese, Japanese, and many others. The language is set in your message compose window. If you write in multiple languages, you can change the language for each message or select multiple languages to check against all of them at once.

Can I turn off spell check completely?

Yes. In Outlook for Windows, go to File > Options > Mail and uncheck "Check spelling as you type". On Mac, go to Outlook > Preferences > Spelling and uncheck the same box. On the web, spell check cannot be turned off — it will always check when you send.