MS Outlook 2007 allows users to speed up and simplify their working experience in many ways. One of such useful features in MS Outlook is the automatic Address completing for frequently used e-mail addresses. The cache for entered e-mail addresses is stored in the AutoComplete file with the extension .NK2 located in the user's profile, for example, in Windows Vista it would be: \users\<username>\AppData\Microsoft\Outlook\<profilename>.NK2

As the user types an address, the cache items matching the letters typed are displayed in a dropdown box. The user can choose the appropriate address by using arrows keys or by selecting an address with the cursor. The AutoComplete file handles up to 1000 entries and stores more than just addresses.

Not everyon emay need this feature, but those who will need will want to know how to enable it and those who will not , - will need to know how to disable it. AutoComplete is easily toggled on or off through Outlook. Navigate to Tools > Options > E-mail Options > Advanced E-mail Options. To disable AutoComplete, clear the checkbox beside the option to Automatic Name Checking and Suggest names while completing To, Cc and Bcc fields options.