Outlook Email Address Auto-Resolution vs. Auto-Complete

Last reviewed on December 7, 2013

All versions of Outlook support Autoresolve. Also known as automatic name checking, this feature allows you to type a name, or even just the first few letters, and the name resolves a few seconds after you tab out of the field. When one match is found, the name has a solid underline. When more than one possible match exist you’ll see a red wavy underline. Right click on it to choose an address. When more than one match exists for a name you’ve used before, Outlook resolves to the last name used and uses a green dotted line to alert you that other possibilities exist. Right click to see the other addresses.

Outlook 2002 and up support Autocomplete. Also known as Suggest Names, this is the feature that shows addresses of people you’ve sent messages to previously and you can select matches as you begin typing. Autocomplete collects the addresses when you send new messages or reply and in later versions, you can seed the list with addresses for your address books. You can clear the autocomplete cache by deleting the *.NK2 file for your profile or delete one address at a time by using the arrow key to select it as you type and then Delete. Like autoresolve, you can turn it on or off in Tools, Options, Email Options, Advanced Options.

See Understanding Outlook’s Auto-Complete Cache (*.NK2) for more information.

Using Auto-Resolution

The best way to make the transition is to understand Outlook's auto-resolution feature. For frequently used names, you can set a nickname that Outlook will automatically resolve to the full address. The nickname needs to be part of the contact's full name. In other words, you won't be able to use "Boss" as the nickname for your boss (unless, of course, his or her name is something like "Boss Tweed"). Here's how to set up a nickname:

  1. Start a new message.
  2. Type the text you want to use for the nickname into the To box.
  3. Fill in the subject and start typing a message.
  4. When you see the name in the To box underlined with a red squiggle, right-click on the name. You'll see a choice of matching names from your address book. Choose the one you want to use or click More Names to get other choices.

Next time you want to send a message to that person, just type in the text from Step 2 again. Outlook will automatically get the address for you and will underline the full name in a dashed green line to highlight that auto-resolution did its job.

There is one limitation that "gets" many users: when you use auto-resolution, Outlook searches the address books in order and when it finds a match in one address book, it stops looking.

Auto-Resolution

All versions of Outlook support Autoresolve. Also known as automatic name checking, this feature allows you to type a name, or even just the first few letters, and the name resolves a few seconds after you tab out of the field. When one match is found, the name has a solid underline. When more than one possible match exist you'll see a red wavy underline. Right click on it to choose an address. When more than one match exists for a name you've used before, Outlook resolves to the last name used and uses a green dotted line to alert you that other possibilities exist. Right click to see the other addresses. When Name checking is disabled in Tools, Options, Email Options, Advanced Options it won't do it as you type the names in but it will check and resolve them when you hit Send. You can force an autoresolve at anytime using Ctrl+K.

Here's some additional information on how multiple address lists, including the GAL, affect the resolution process.

What fields does Outlook use to look up names for address resolution? It depends on the address list. For the Exchange Global Address List (GAL), it searches several fields -- display name, surname, mailbox alias and office (but, significantly, not first name).

For Contacts and Personal Address Book, the search fields include name and email address fields, but *not* the Nickname field on contacts.

Name resolution searches only one address list at a time. Use the Address book's Tools, Options dialog to control the order in which lists are searched in Outlook. Let's say you have the GAL set as the first list, followed by more than one Contacts folder. If there are matches in the GAL, you won't see any addresses from Contacts. If there is no match in the GAL, then it searches the first Contacts folder in the list. If no matches in that contacts folder, then it searches the next Contacts folder. If you think about performance, this makes a lot of sense. Searching across all address lists in your name resolution list could take a very long time.

For example, entering "William" and pressing Ctrl+K might display a list that includes William Gates, Bart Williamson, and Jane Williams. If there are no matches in the GAL for William, then you might also get names from the PAB with addresses like williamg@domain.dom. The search is always a "starts with" search, looking only at the beginning of the fields. It would not find a name like Alice Fitz-Williams because "Williams" here is not at the beginning of the surname.

Disable Auto-Resolution and/or Auto-Complete

Autocomplete and autoresolve options dialogIf you prefer not to use Auto-Resolution (1), you can disable it in Tools, Options, E-mail Options, Advanced E-mail Options, Automatic name checking. When this is turned off, Outlook will still resolve the names, but not immediately. You can press Ctrl+K to force auto-resolution at any time before sending the message; otherwise Outlook will always resolve the address when you send the message. If a match isn’t found, you’ll be asked to pick names using the Check Names dialog.

To disable Auto-complete (2) in Outlook 2007 and older, go to Tools, Options, Preferences, E-mail Options, Advanced and deselect ‘Suggest names while completing to To, CC, BCC fields’

The following tools can be used to view the contents of the auto-complete cache.

Tools

debunk2

Open source project to read MS Outlook autocomplete (NK2) files and extract email addresses. Beta version 0.5

Ingresssor

Use Ingresssor (formerly OwtLook) to edit the NK2 file

NK2Edit

Use NK2Edit to edit or delete information stored in the NK2 file or Outlook 2010/2013's Autocomplete Stream, including the display name, the email address, the exchange string, the Drop-Down display name, and the search string. Free for home use; Commercial license available.

NK2View

Use NK2View to view, edit or delete entries in Outlook's .NK2 AutoComplete file. Export the records to text, html, or xml files. Freeware. Version 1.37

Written by

Diane Poremsky
A Microsoft Outlook Most Valuable Professional (MVP) since 1999, Diane is the author of several books, including Outlook 2013 Absolute Beginners Book. She also created video training CDs and online training classes for Microsoft Outlook. You can find her helping people online in Outlook Forums as well as in the Microsoft Answers and TechNet forums.

Please post long or more complicated questions at Outlookforums.

3 responses to “Address Auto-Resolution vs. Auto-Complete”

  1. Trudy Licano

    We are using Windows Pro 7 and Office 10 and about to move our emails to a MS Exchange Server. Up until now we have had our own in-house server. The question is this: Is there a way to set it up so each of us only pull contact information from one Shared Contact Folder (cache) and our autofills or when we use Check Names, both of those pull from only the Shared Contact Folder (cache)? Up until now autofills and using Check Names draws from each person's personal contact folder and as the owner of the company I don't anyone to have a separate contact folder because then we are out of sync with updates one person has and another doesn't. Btw, for 30 years my staff has been approximately 5-7 members, so not a large workgroup but still making sure everyone is in sync with contact information is important. I don't allow personal contacts to be on our computers. It's 'business only' contacts and each of us have access to those contacts' information.

  2. Trudy Licano

    Thanks, Diane for your prompt response. I'm mystified that MS would sell workgroup software like Outlook, shared folders, shared calendar, and yet there's no option make the shared folder the automatic "go-to" folder for auto-fills and Check Names. Sigh - really, Microsoft, what are you thinking! Okay, thanks, Diane. Regards, Trudy Licano

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