Wednesday, 12 Jun 2024

The Outlook AutoComplete List

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Microsoft Outlook maintains the AutoComplete list, also known as the nickname cache. This list is generated automatically when you send email messages from Outlook and contains SMTP addresses, LegacyExchangeDN entries, and display names for your contacts.

Limited Number of Entries

Outlook has a limit on the number of entries you can save in the AutoComplete list. Once you reach this limit, Outlook will remove names from the list based on usage weighting. To avoid losing important contacts, you can proactively remove entries that you no longer need or increase the limit for the nickname cache. However, increasing the limit is not recommended as it can lead to corruption and loss of cached entries.

  • The AutoComplete list limits are as follows:
    • Outlook 2019: 1,000 entries
    • Outlook 2016: 1,000 entries
    • Outlook 2013: 1,000 entries
    • Outlook 2010: 1,000 entries

Enable the AutoComplete Feature

To access the AutoComplete setting in Outlook, follow these steps:

  1. On the File menu, select Options.
  2. Select the Mail tab.
  3. Scroll down until you see Send messages and make sure the Use Auto-Complete List to suggest names when typing in the To, Cc, and Bcc lines box is checked.

Copy the AutoComplete List

Different versions of Outlook store the AutoComplete list in different ways. Outlook 2007 and earlier versions use a nickname (.nk2) file, while Outlook 2021, 2019, 2016, 2013, and 2010 store the list as a hidden message in your primary message store. You can also import older .nk2 files.

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Remove AutoComplete List Entries One at a Time

If you need to remove specific entries from the AutoComplete list, follow these steps:

  1. Open a new email message.
  2. Type the first few characters of the entry you want to remove.
  3. When the entry appears in the suggestion list, move your mouse over it until it becomes highlighted.
  4. Click the X icon next to the highlighted suggestion or press the Delete key on your keyboard.

Please note that removing an entry from the AutoComplete list will prevent it from appearing again, but it won’t delete the entry from your account. The name may still appear in other areas of Outlook, such as search boxes.

Clear the AutoComplete List

To delete the entire AutoComplete list, you can choose one of the following methods:

Method 1

  1. Open Outlook.
  2. On the File tab, select Options.
  3. Select the Mail tab.
  4. Under Send Messages, select Empty Auto-Complete List.
  5. Click Yes to confirm.

Method 2

  1. Select Start, and then Run.
  2. Type Outlook.exe /CleanAutoCompleteCache.

Please be aware that using the second method requires specifying the path to Outlook.exe if Outlook is not installed in the default location.

Known Issues in the AutoComplete Cache

Over time, the AutoComplete cache can become corrupted and may not save new entries. If this happens, you can try removing entries one at a time or clearing the entire list.

Change the Limit for the AutoComplete List

Modifying the limit for the AutoComplete list is not recommended as it can lead to corruption and loss of data. However, if you still want to proceed, use the following steps:

  1. Exit Outlook.
  2. Start Registry Editor.
  3. Locate and select the following registry subkey: HKEY_CURRENT_USERSoftwareMicrosoftOffice<x.0>OutlookAutoNameCheck (The placeholder <x.0> represents your version of Microsoft Office. Refer to the list above for the appropriate value.)
  4. On the Edit menu, point to New, and then select DWORD value.
  5. Type MaxNickNames and press Enter.
  6. On the Edit menu, select Modify.
  7. Enter the new value for the limit and click OK. Please make sure to type the number in decimal form.
  8. Exit Registry Editor.
  9. Start Outlook.
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Note that the MaxNickNames registry value only specifies the non-default limit and can also be used to lower the limit of the nickname cache.

Frequently Asked Questions

Q: Is the AutoComplete list shared with Outlook on the web?
A: No, the AutoComplete list for Outlook is specific to the Outlook desktop application and is not shared with Outlook on the web.

Q: Can I restore a name to the AutoComplete list after removing it?
A: If you send a new email to a person after removing their name from the AutoComplete list, their information will be automatically restored.

Q: How can I clear the AutoComplete list in Outlook?
A: You can either select the “Empty Auto-Complete List” option in the Mail settings or use the /CleanAutoCompleteCache switch when starting Outlook.


The AutoComplete list in Microsoft Outlook is a convenient feature that saves you time by suggesting names as you type in the To, Cc, and Bcc lines. By understanding how the list works and how to manage it effectively, you can ensure a streamlined and hassle-free email experience. For more information and resources on technology-related topics, visit Eireview.