Spell Check Runs Automatically in Outlook

Spell check in Outlook works in the background as you type — you do not need to turn it on or hunt for a button. Red squiggly lines appear under words Outlook does not recognize, and you can right-click any underlined word to see suggestions or add it to your dictionary. The feature works the same way in Outlook on Windows, Mac, and the web version.

If you do not see red lines under misspelled words, spell check may be turned off in your settings. The location of the on-off switch depends on which version of Outlook you use, but the process takes less than a minute once you know where to look.

Key Takeaways

  • Spell check in Outlook marks questionable words with red underlines as you type, without requiring you to start a separate check.
  • Right-click any red-underlined word to see correction suggestions, ignore it for this message only, or add it permanently to your dictionary.
  • In Outlook on Windows, turn spell check on or off under File > Options > Mail > Spelling and Autocorrect.
  • In Outlook on Mac, the setting is under Outlook > Preferences > Spelling and Grammar.
  • Outlook on the web (Outlook.com) checks spelling automatically and does not have a separate toggle to disable it.

How to Turn On Spell Check in Outlook on Windows

Open Outlook and click the File menu in the top left corner. From the dropdown, select Options. In the left sidebar of the Options window, click Mail. Scroll down until you see the section labeled Spelling and Autocorrect.

Look for the checkbox next to Always suggest replacements for misspelled words. If it is unchecked, click it to turn spell check on. You will also see a checkbox for Ignore words in UPPERCASE and Ignore words with numbers — these let you skip certain types of words if they appear in your messages. Once you have made your choices, click OK at the bottom of the window. Spell check will now mark errors with red lines as you compose new messages.

How to Turn On Spell Check in Outlook on Mac

Click Outlook in the menu bar at the top of your screen, then select Preferences from the dropdown. In the Preferences window, find and click Spelling and Grammar. You will see a checkbox for Check spelling while you type — make sure it is checked.

Below that option, you can choose which language Outlook uses for spell check. If you write in multiple languages, you can set Outlook to check against more than one dictionary. Once your settings are correct, close the Preferences window. The next time you compose a message, red underlines will appear under words Outlook does not recognize.

How to Correct a Misspelled Word

When you see a red underline under a word, right-click directly on that word. A small menu will appear with several options. At the top, you will see suggested corrections — click any suggestion to replace the misspelled word when ready.

If the word is spelled correctly but Outlook does not recognize it (a name, a technical term, or a brand), you have two choices. Click Add to Dictionary to teach Outlook this word permanently, so it will never flag it again in any message. Click Ignore All to skip this word only in the current message. The next time you use that word in a different message, Outlook will flag it again unless you added it to the dictionary.

Spell Check in Outlook on the Web

If you use Outlook through a web browser (Outlook.com or Outlook on Microsoft 365 online), spell check is always on and cannot be turned off. As you type in the message body, Outlook marks misspelled words with a red underline. Right-click the underlined word to see suggestions, just as you would in the desktop version.

The web version does not have a settings menu for spell check because Microsoft manages it centrally. If you prefer to use a different spell-checking tool or want more control over the feature, you may want to use the desktop version of Outlook instead, where you can adjust the settings described above.

Why Spell Check Might Not Be Working

If you have turned on spell check but still do not see red underlines, the most common reason is that you are composing in Plain Text format instead of HTML or Rich Text. Outlook does not check spelling in plain text messages. To change the format, open a new message, click the Format Text tab at the top, and select either HTML or Rich Text. Spell check will now work in that message and any future ones you compose in that format.

Another reason spell check might seem inactive is if you are using an older version of Outlook that is no longer receiving updates. If you have not updated Outlook in several months, check for updates through File > Office Account > Update Options. Updating often restores features that may have stopped working.

Using the Dictionary to Improve Spell Check Over Time

Every time you click Add to Dictionary for a word, you are training Outlook to recognize it. This is especially useful if you write about a specific field — medical terms, software names, client names, or industry jargon will stop being flagged once you add them. Your dictionary is personal to your Outlook account, so the words you add will follow you if you use Outlook on multiple devices.

If you add a word by mistake and want to remove it, the process varies by version. In Outlook on Windows, go to File > Options > Mail > Spelling and Autocorrect > Custom Dictionaries, select the dictionary you use, and click Edit Word List to remove entries. In Outlook on Mac, there is no built-in way to edit the dictionary — you would need to reinstall Outlook to clear it completely. For this reason, take a moment before clicking Add to Dictionary to make sure the word is spelled the way you want it.

Frequently Asked Questions

Can I spell check a message I already sent?

No. Spell check only works while you are composing a message, before you click Send. Once a message is sent, you cannot edit it in Outlook on Windows or Mac. In Outlook on the web, you can edit a message within 60 seconds of sending it — make your changes and click Save, and spell check will explore to the updated version.

Does spell check work in subject lines?

Yes. Spell check marks errors in the subject line the same way it marks them in the message body. Right-click any underlined word in the subject to see suggestions or add it to your dictionary.

What language does Outlook spell check use?

Outlook uses the language you set in your Windows or Mac system settings by default. In Outlook on Mac, you can change the spell-check language in Preferences > Spelling and Grammar. In Outlook on Windows, the language is tied to your Office installation language, which you can change through File > Options > Language.

Why does spell check flag words I know are correct?

Outlook's dictionary does not include every word in the English language, especially proper nouns, technical terms, and newer words. If a word is correct, click Add to Dictionary and Outlook will stop flagging it. You can also click Ignore All if you only want to skip it in the current message.

Can I turn off spell check for just one message?

Not directly. Spell check is either on or off for all your messages. However, you can ignore individual words by right-clicking and selecting Ignore All, which will skip that word only in the current message. If you need to turn spell check off entirely, use the settings described in the sections above for your version of Outlook.