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

Spell check is a tool that flags words it does not recognize — usually misspellings — with a red underline as you type. In Outlook, spell check runs automatically on emails you compose. If you are not seeing red underlines under words you know are wrong, spell check is likely turned off. You can turn it back on in a few clicks, and the setting is the same whether you use Outlook on Windows, Mac, or the web version.

The steps differ slightly depending on which version of Outlook you have. Outlook 2019 and Outlook 2021 (the versions you buy once and install on your computer) have spell check in one place. Outlook 365 (the subscription version) and Outlook on the web (the version you access through a browser) have it in another. All versions let you turn spell check on and off, and all let you add words to your personal dictionary so Outlook stops flagging them.

Key Takeaways

  • Spell check in Outlook is turned on by default, but you can turn it off in settings and turn it back on the same way.
  • In Outlook 2019 and 2021 on Windows, go to File, then Options, then Mail, then Spelling and Autocorrect, then check the box next to "Check spelling as you type".
  • In Outlook on Mac, go to Outlook, then Preferences, then Spelling and Grammar, then check "Check spelling as you type".
  • In Outlook on the web, go to Settings, then Mail, then Compose and reply, then turn on "Spelling suggestions".
  • You can right-click any flagged word to see suggestions, ignore it once, or add it to your dictionary so Outlook never flags it again.

Turning on spell check in Outlook on Windows

Open Outlook and click the File menu in the top left corner. From the dropdown, click Options. A window will open with a list of categories on the left side. Click Mail. Scroll down until you see the section called "Spelling and Autocorrect". Look for the checkbox next to "Check spelling as you type" and click it to turn spell check on. If the box is already checked, spell check is already on.

Once you have checked that box, click OK at the bottom of the window to save your changes. Close and reopen Outlook, or start composing a new email. You should now see red underlines appear under words Outlook does not recognize. If you still do not see them, make sure you clicked OK and that the checkbox is actually filled in — sometimes the click does not register the first time.

Turning on spell check in Outlook on Mac

Open Outlook and click Outlook in the menu bar at the very top of your screen. From the dropdown, click Preferences. A window will open. Look for the section called Spelling and Grammar and click it. You will see a checkbox next to "Check spelling as you type". Click the checkbox to turn spell check on.

Close the Preferences window. The next time you compose an email, spell check will be active. Words Outlook does not recognize will appear with a red underline. If you do not see underlines, go back to Preferences, Spelling and Grammar, and make sure the checkbox is filled in.

Turning on spell check in Outlook on the web

Go to Outlook.com or your organization's Outlook web address and sign in. Click the gear icon in the top right corner of the screen. From the dropdown menu, click Settings. A new page will open. On the left side, click Mail. Scroll down until you see "Compose and reply". Under that section, look for "Spelling suggestions" and click the toggle to turn it on. The toggle should turn blue when it is on.

Close the Settings page and go back to your inbox. The next time you compose an email, spell check will flag misspelled words. In Outlook on the web, flagged words appear with a red underline, just like in the desktop versions.

What to do when spell check flags a word

When you see a red underline under a word, right-click it (or on Mac, Control-click it). A menu will appear with options. If Outlook has suggestions for what the word should be, you will see them listed at the top. Click any suggestion to replace the word. If the word is spelled correctly but Outlook does not recognize it — for example, a person's name or a technical term — you have two other options.

Click "Ignore" to skip that word just this one time. The next time you use the same word in a different email, Outlook will flag it again. If you want Outlook to never flag the word again, click "Add to Dictionary". Outlook will remember that word and will not underline it in any future emails. This is useful for names, company terms, or specialized vocabulary you use regularly.

Spell check does not catch every mistake

Spell check only catches words it does not recognize in its dictionary. It does not catch words that are spelled correctly but used in the wrong context — for example, "their" instead of "there", or "its" instead of "it's". It also does not catch grammar mistakes like run-on sentences or missing punctuation. Spell check is a useful first pass, but it is not a replacement for reading your email before you send it.

If you want more thorough checking, some versions of Outlook can use the Editor tool, which checks grammar and style in addition to spelling. In Outlook on the web and Outlook 365, you can turn on Editor by going to Settings, Mail, Compose and reply, and looking for "Editor". On older versions of Outlook, Editor may not be available.

Spell check settings you can customize

In Outlook on Windows, you can control more than just whether spell check is on. In the same Spelling and Autocorrect section where you turned on spell check, you can also choose which language Outlook uses to check spelling. If you write emails in multiple languages, you can set Outlook to check in a specific language, or you can turn off spell check for a particular language if you use it frequently and do not want constant red underlines.

You can also tell Outlook to ignore words in all capital letters, words with numbers, or words with mixed case. These settings are useful if you work with acronyms, product codes, or technical terms that do not follow standard capitalization. Experiment with these options to find what works best for the way you write.

Frequently Asked Questions

Why is spell check not working even though I turned it on?

Make sure you clicked OK or saved your settings after turning it on. Close Outlook completely and reopen it — sometimes the change does not take effect until you restart the program. If you are using Outlook on the web, try clearing your browser cache or using a different browser. If spell check is still not working, your organization may have disabled it in your account settings.

Can I turn off spell check for just one email?

No, spell check is an all-or-nothing setting in Outlook. If you turn it on, it will check every email you compose. You can ignore individual flagged words by right-clicking and selecting "Ignore", but you cannot disable spell check for a single message without turning it off entirely in settings.

What if Outlook keeps flagging a word I use all the time?

Right-click the word and click "Add to Dictionary". Outlook will stop flagging it in any future emails. If you add it by mistake, you can remove it later by going back to Spelling and Autocorrect settings (Windows) or Spelling and Grammar preferences (Mac) and looking for an option to manage your custom dictionary.

Does spell check work the same way in Outlook and Gmail?

No. Gmail has spell check built in, but you turn it on differently — usually through browser settings or Gmail's own settings menu. The red underlines work the same way, but the menus and options are in different places. If you use both, you will need to learn the steps for each one separately.

Can I use spell check in other languages?

Yes. In Outlook on Windows, go to Spelling and Autocorrect settings and look for the language dropdown. Select the language you want to check. On Mac, go to Spelling and Grammar preferences and choose your language. Outlook will then flag words that do not match that language's dictionary.