There’s a small utility named NK2View by the excellent Nirsoft that can help with this problem. You can delete items in the list, import from your address book, and even export auto-completed addresses for later import into Outlook as full contacts.
View/Delete AutoComplete Items
The utility should automatically detect the location of your *.nk2 folder, but if it doesn’t you’ll find it in the following location:
You can select items in the list and use the Delete key to get rid of them. You’ll be warned that you should probably close Outlook first.
Unfortunately, you can’t directly edit the items in the list, you can just view them with a double-click.
Import Outlook Contacts to Your Auto-Complete List
You can import contacts from the Address Book, or even the Global Address List if you are on an Exchange network. Just go to the File \ Add Items From Address Book item on the menu.
Select the address book you want, and then add the selected items by using the To button.
After you hit the OK button, the items will be added to the list.
Export Your AutoComplete List
You can export the items in the list into a format that could be imported into Outlook, where you can make any edits you’d like. Choose “Save Selected Items” from the menu (make sure to select contacts first)
Then choose “Tab delimited file – for Outlook import” from the list, and name the file something useful.
Import Auto-Complete Entries into Outlook as Contacts
Open Outlook and go to File \ Import and Export on the menu.
Choose to “Import from another program or file” and hit Next.
Choose to import “Tab Separated Values (Windows)” from the file type list.
Choose the file to import from, and then choose to “Do not import duplicate items”. You don’t want the items in the auto-complete to overwrite existing entries in your list, the idea is to populate only the items missing from your contacts folder.
You’ll be prompted for the folder you want to import to, then on the next screen check the box next to “Import filename into folder: Contacts”, and the mapping dialog will immediately pop up.
Here’s where it’s slightly tricky… you need to map between the left and right hand panes by dragging and dropping the values where you want them. Here’s what I’d suggest as the mappings:
Email Address -> E-mail Email Display Name -> Name
Hit OK and then Finish on the other screen, and your contacts will be immediately imported.
Editing Auto-Complete Entries
Since you can’t use the utility to edit items, what I’d suggest you do is export the items and import them into your Outlook contacts folder, then use the utility to import from your address book after you’ve made your edits in Outlook.
Download NK2View from nirsoft.net
