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

Spell check in Outlook runs as you type and marks misspelled words with a red underline. In most cases, it is already active — you do not have to do anything. If you are not seeing red underlines under words you know are wrong, spell check has been turned off, and you can turn it back on in a few clicks.

The steps differ slightly between Outlook on the web (the version you use in a browser) and Outlook on your computer. Both take less than a minute. Once it is on, Outlook will flag potential spelling errors before you send, which helps you catch mistakes and keeps your messages looking professional.

Key Takeaways

  • Spell check is enabled by default in Outlook, so if you see red underlines under words, it is already working.
  • In Outlook on your computer, turn spell check back on by going to File > Options > Mail > Spelling and Autocorrect, then checking "Always suggest replacements for misspelled words."
  • In Outlook on the web, spell check is always on and cannot be turned off, but you can right-click misspelled words to see suggestions.
  • Red underlines appear only in the message body, not in the subject line, so proofread subjects separately before sending.

How to turn spell check on in Outlook on your computer

Open Outlook and click the File menu in the top left corner. From the dropdown, select Options. In the Outlook Options window, click Mail on the left side. Scroll down until you see the section labeled "Spelling and Autocorrect" and look for the checkbox next to "Always suggest replacements for misspelled words." If the box is empty, click it to enable spell check.

Once you have checked that box, click OK at the bottom of the window. Spell check will now be active. The next time you type a message, misspelled words will appear with a red underline. Right-click any underlined word to see correction suggestions, or straightforward continue typing and fix it later.

How to turn spell check on in Outlook on the web

Spell check in Outlook on the web (the version you access through a browser) is always on and cannot be disabled. If you are not seeing red underlines under misspelled words, the issue is usually that Outlook is not recognizing the word as wrong — this happens with proper nouns, technical terms, or words not in its dictionary.

To correct a word, right-click it directly in the message body. A menu will appear with spelling suggestions. Click the correct spelling to replace the word. If Outlook keeps flagging a word you know is correct, you can right-click it and select "Add to dictionary" so it stops marking it as an error in the future.

Why spell check might not be working even after you turn it on

If you have enabled spell check but still do not see red underlines, check whether you are using a different language setting. Outlook spell checks against the language you have selected in your settings. If your language is set to something other than English, it will check spelling against that language's rules instead.

To change the language in Outlook on your computer, go to File > Options > Language. Make sure the language matches the one you are typing in. In Outlook on the web, click the Settings gear icon, then Language and Time Zone, and confirm the language is correct. Another common reason is that Outlook straightforward has not caught up yet — wait a few seconds after typing a word before expecting the underline to appear.

How to fix a misspelled word once spell check flags it

Right-click any word with a red underline. A small menu will pop up showing suggested corrections at the top. Click the correct spelling to replace the word when ready. If none of the suggestions are right, you can click in the message and edit the word yourself by hand.

If Outlook keeps flagging a word that is actually correct — a name, a brand, or a technical term — right-click it and select "Add to dictionary" or "Ignore all." This tells Outlook to stop marking that word as wrong in future messages. Use "Ignore all" if you only want to ignore it in the current message, or "Add to dictionary" if you want Outlook to remember it permanently.

Spell check does not cover subject lines or some other fields

Spell check in Outlook works only in the message body, not in the subject line. This means typos in your subject line will not be caught automatically. Before you send any email, take a moment to read the subject line out loud to yourself — this catches most mistakes that spell check cannot.

The same applies to the To, Cc, and Bcc fields. Spell check does not monitor those areas, so if you are typing a recipient's name or email address, you are on your own. Double-check recipient names and addresses before sending, especially if you are writing to someone for the first time or if the name is unusual.

Frequently Asked Questions

Can I turn off spell check in Outlook?

In Outlook on your computer, yes — go to File > Options > Mail > Spelling and Autocorrect and uncheck "Always suggest replacements for misspelled words." In Outlook on the web, spell check is always on and cannot be disabled.

Why does Outlook flag words I know are spelled correctly?

Outlook's dictionary does not include every word, especially proper nouns, brand names, and technical terms. Right-click the word and select "Add to dictionary" to stop Outlook from flagging it in the future.

Does spell check work in emails I receive, or only in emails I write?

Spell check only works in messages you are composing. It does not check emails you receive or flag errors in other people's messages.

What language does Outlook spell check use?

Outlook uses the language you have set in your account settings. Check File > Options > Language (on your computer) or Settings > Language and Time Zone (on the web) to confirm it matches the language you are typing in.