Outlook Auto-Complete List: Enable & Manage
To enable the Outlook auto-complete list (the suggested email addresses that appear as you type in the To, Cc, and Bcc fields), go to File > Options > Mail and under “Send messages,” check the box for “Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines.” This setting is on by default in most versions, but it can be turned off or cleared, and this article explains how to manage it, fix common issues, and understand how the feature stores your data.
What Is the Auto-Complete List?
The auto-complete list is a feature in Microsoft Outlook that remembers email addresses you have sent messages to. When you start typing a name or address in the To, Cc, or Bcc field, Outlook displays a dropdown of matching suggestions based on your past activity. This is not the same as the Contacts folder or the Global Address List (GAL); it is a separate, cached list stored locally on your computer. The list is sometimes called the “nickname cache” because it works like Outlook’s memory of who you email most often.
How to Enable or Disable Auto-Complete
The steps are nearly identical across Outlook 2016, 2019, 2021, and Microsoft 365. For Outlook on the web (OWA), the setting is found in a different location.
- Open Outlook and click File in the top-left corner.
- Click Options at the bottom of the left-hand menu.
- In the Mail category, scroll down to the Send messages section.
- Check or uncheck Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines.
- Click OK to save your changes.
If you uncheck this box, Outlook will stop suggesting addresses, but it will not delete the existing list. To turn it back on, simply re-check the box.
How to Clear the Auto-Complete List
Sometimes the list becomes cluttered with outdated or incorrect addresses. You can remove individual entries or wipe the entire list.
- Remove one entry: Start typing the address in a new message. When the suggestion appears, hover over it and click the X that appears to the right.
- Clear all entries: Go to File > Options > Mail, scroll to Send messages, and click the Empty Auto-Complete List button. Confirm when prompted.
Note that clearing the list is permanent; you cannot undo it. You will have to rebuild the list by sending new emails.
Why Is Auto-Complete Not Working?
If the feature is enabled but suggestions are not appearing, try these common fixes:
- Check the setting: Make sure the checkbox is still ticked. Some updates or IT policies can reset it.
- Restart Outlook: The auto-complete cache is loaded at startup. A full restart can reload it.
- Check if you’re in Online mode: In cached Exchange mode, the list works normally. In Online mode, some versions have issues; switch to cached mode if possible.
- Repair the NK2 file (older versions): In Outlook 2010 and earlier, the list was stored in a .nk2 file. If it’s corrupted, you may need to delete it (Outlook will recreate it). In newer versions, the list is stored in the mailbox or a local profile, so this fix does not apply.
- Check for add-ins: Third-party add-ins can interfere. Disable them temporarily to test.
Auto-Complete vs. Contacts vs. GAL
It’s easy to confuse these three sources of addresses. Auto-complete draws from your sent-mail history. Contacts are your manually created entries in the People folder. The Global Address List (GAL) is the company-wide directory provided by your Exchange server. When you type in the To field, Outlook combines suggestions from all three, but it marks auto-complete entries with a person icon and no contact details. If you delete a contact, the auto-complete entry may still appear because it’s a separate record.
Where Is the Auto-Complete List Stored?
In Outlook 2013 and later, the auto-complete list is stored in a hidden folder within your mailbox (if you use an Exchange account) or in a local data file (.ost or .pst). This means it roams with your profile if you use the same account on multiple computers, as long as you use cached mode. For POP/IMAP accounts, the list is stored locally and may not sync across devices. There is no simple file you can back up manually; the recommended way to transfer it is to use the built-in export/import of the auto-complete list via the “Export” and “Import” commands in the File > Options > Mail section.
Frequently Asked Questions
How do I add an address to the auto-complete list?
You don’t add addresses manually. The list is built automatically when you send a message to a new recipient. Once you send, that address becomes a candidate for future suggestions.
Can I reorder the auto-complete suggestions?
No, Outlook does not let you manually reorder the list. It uses a frequency-based algorithm: addresses you email most often appear higher. The more you send to a person, the higher they rank.
Does the auto-complete list sync with Outlook on the web?
If you use Microsoft 365 or Exchange, the list is stored in your mailbox, so it syncs across Outlook desktop, Outlook on the web, and the mobile app. For POP/IMAP accounts, it does not sync.
Why does an old email address keep appearing?
Outlook remembers every address you’ve sent to, even if you later change the contact’s address. To remove it, hover over the suggestion and click the X. You may need to do this multiple times if the address appears in different forms (e.g., with or without a display name).
Is the auto-complete list the same as the “Recent People” list?
No. “Recent People” is a separate feature that shows people you’ve interacted with recently in the People view. The auto-complete list is specifically for the To, Cc, and Bcc fields.
Can I export the auto-complete list to another computer?
Yes. In File > Options > Mail, under “Send messages,” click “Export” to save the list to a .nk2 file (or a similar format). On the new computer, click “Import” and select that file. This works in most versions, but the exact file extension may vary.
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