How To Clear the Outlook Email Address Auto Complete Cache

Delete Auto Complete Outlook Information

Microsoft Outlook has had a feature called Email Address Auto Complete since Outlook 2003, and many of us take this feature for granted. This feature works as you type an email address into the TO: CC: or BCC: fields, Outlook then begins to display a list of display names and email addresses from the Outlook Auto Complete cache – these are email addresses you’ve already used and that it remembers for you.

Seems simple enough; so what’s the problem?

This great feature has one flaw, the Outlook Auto Complete Cache is a static file – this means it doesn’t update as details change, and as it caches more than just an email address, it can cause other issues too. Here we will explain one scenario experienced by one of our customers, and how to resolve the potential issues.

The Scenario

Your organisation uses Microsoft Exchange or Office 365 email accounts and had an employee called John Doe who had a email address like john@yourcompanyname.co.uk. John Doe left the organisation and his account was deleted from your Microsoft Exchange Server / Microsoft Hosted Exchange or Office 365 account. Several months or years later, another John joins the organisation and is given an email address, john@yourcompanyname.co.uk. His email account works great, but as more people start communicating with John they notice that the display name is John Doe or that the picture associated with the new John shows a picture of John Doe (the ex employee) – this is the Auto Complete Cache for Outlook doing its thing. Everybody that emailed the original John Doe may experience this and can become a bit of a nuisance.

The resolution

This very much depends on which version of Outlook you are using, but will list all the methods below.

How to remove nickname cache entries, one at a time.

Outlook 2010 and later versions

  1. Open a new email message.
  2. Type the first few characters of the nickname cache entry that you want to remove from the cache.
  3. When the entry appears in the list of suggested names, move your mouse pointer over the name until it becomes highlighted, but do not click the name.
  4. When the “X” icon appears next to the highlighted name, click X to remove the name from the list.

Outlook 2007 or Outlook 2003

  1. Open a new email message.
  2. Type the first few characters of the nickname cache entry that you want to remove from the cache.
  3. When the entry appears in the list of suggested names, use the UP and DOWN arrow keys on your keyboard to select the entry, and then press DELETE on your keyboard.

How to clear the whole nickname cache this will remove all auto complete data, and start adding them back as you continue to use Outlook.

Microsoft have a downloadable tool which can do this for you, this can be downloaded below.

To fix this problem automatically, click on the appropriate Download Here link below. In the File Download dialog box, click Run or Open , and then follow the steps in the easy fix wizard.

  • This wizard may be in English only. However, the automatic fix also works for other language versions of Windows.
  • If you’re not on the computer that has the problem, save the easy fix solution to a flash drive or a CD, and then run it on the computer that has the problem.

For Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows Server 2012 R2 or Windows Server 2008 R2DOWNLOAD HERE

For Windows Vista, Windows Server 2008 or Windows Server 2003 – DOWNLOAD HERE

Want to fix it yourself? 

Outlook 2010 and later versions

To reset the whole Outlook nickname cache for Outlook 2010 and later versions, use one of the following methods:

Method 1
  1. Open Outlook.
  2. On the File tab, click Options.
    The screen shot for this step
  3. Click the Mail tab.
    The screen shot for this step
  4. Under Send Messages, click Empty Auto-Complete List.
  5. Click Yes.

Outlook will generate a new nickname cache.

Method 2
  1. Click Start, and then click Run.
  2. Start Outlook by using the /CleanAutoCompleteCache switch. To do this, type Outlook.exe /CleanAutoCompleteCacheNote If Outlook is not installed in the default location, you must point to the path of Outlook.exe.

Outlook will generate a new nickname cache.

Outlook 2002 through Outlook 2007

Windows 7 or Windows Vista

To reset the whole Outlook nickname cache, follow these steps:

  1. Exit Outlook.
  2. Click Start, and then click Computer.
    The screen shot for this step
  3. Click Organize, and then click Folder and search options.
    The screen shot for this step
  4. On the View tab, click Show hidden files, folders, and drives.
    The screen shot for this step
  5. Click OK.
  6. Click Start, click All Programs, click Accessories, and then click Run.
  7. In the Run dialog box, type the following command (including the quotation marks), and then click OK:

    “C:\ Users\UserName\AppData\Roaming\Microsoft\Outlook”
    NoteUsername in this path is the name of the currently logged on Windows user.
  8. Right-click the .NK2 file that has name of the profile that you want to reset, and then click Rename.
  9. Rename the file as profilename.bak, and then press Enter.
  10. Start Outlook.
Windows XP

To reset the whole Outlook nickname cache, follow these steps:

  1. Exit Outlook.
  2. Click Start, and then click Search.
  3. In the Search Companion panel on the left, click All files or folders.
  4. In the All or part of the file name: box, type *.NK2.
  5. In the Look In box, click to select your local hard disk.
  6. Click More advanced options, and then click to select the Search hidden files and folders check box.
  7. Click Search.
  8. Right-click the .NK2 file that has the name of the profile that you want to reset, and then click Rename.
  9. Rename the file to profilename.bak, and then press Enter.
  10. Close Windows Explorer.
  11. Restart Outlook.

Outlook will generate a new nickname cache.

To reset the Outlook nickname cache for Microsoft Windows 2000 and Microsoft Windows Millennium Edition (Me), follow these steps:

  1. Exit Outlook.
  2. Start Windows Explorer.
  3. On the Tools menu, click Folder Options, and then click the View tab.
  4. Under Advanced Settings, click to select the Show hidden files and folders check box.
  5. Click OK.
  6. Click Start, point to Search, and then click For Files or Folders.
  7. In the Search for Files and Folders box, type *.NK2 in the Search for files or folders named box.
  8. In the Look In box, click to select your local hard disk.
  9. Click Search Now.
  10. Right-click the .NK2 file that has the name of the profile that you want to reset, and then click Rename.
  11. Rename the file to profilename.bak, and then press Enter.
  12. Close Windows Explorer.
  13. Restart Outlook.

Outlook will generate a new nickname cache.

To reset the Outlook nickname cache for both Microsoft Windows NT 4.0 and Microsoft Windows 98, follow these steps:

  1. Exit Outlook.
  2. Start Windows Explorer.
  3. On the Tools menu, click Folder Options, and then click the View tab.
  4. Under Advanced Settings, click to select the Show all files check box.
  5. Click OK.
  6. Click Start, point to Search, and then click For Files or Folders.
  7. In the Named box, type *.NK2.
  8. In the Look In box, click to select your local hard disk.
  9. Click Find Now.
  10. Right-click the .NK2 file that has the name of the profile that you want to reset, and then click Rename.
  11. Rename the file to profilename.bak, and then press Enter.
  12. Close Windows Explorer.
  13. Restart Outlook.

Outlook will generate a new nickname cache.

So there you have it, that is how to clear both individual email addresses from the Auto Complete Cache or the entire cache on all past and present versions of Outlook and Windows.

Luke Scudder

I am one of the directors here at Tewktech - generally responsible for our client websites, seo, web hosting and server networks, but I'm not afraid to roll up my sleeves and get my hands dirty troubleshooting Windows desktops and servers or delving into hardware diagnostics and repairs.

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