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Where do Outlook's auto-complete suggestions come from?

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Summary: Outlook tries to be helpful when you begin typing an email address by suggesting possibilities. But where those suggestions come from is not simple.

Where do Outlook's auto-complete suggestions come from?

Outlook's auto-complete feature attempts to be helpful by suggesting email names that are similar to what you're typing. A couple of keystrokes, an auto-complete suggestion, and you don't have to type the entire email name every time. Seems both simple and handy.

Unfortunately it's not quite simple, and it can be both handy and frustrating because email names you expect to be present aren't, and those that you never want to look at again keep popping up.

A little bit of understanding and a few tips will go a long way to making this feature more helpful.

To answer the question, the auto-complete suggestions come from something called the nickname list and your address book. Usually.

The nickname list is something that Outlook builds over time as you send and receive email. Essentially it collects all the email addresses that you've sent email to as they've appeared in the To, Cc or Bcc fields. That's Outlook's first source of auto-complete suggestions.

Outlook also appears to sometimes take suggestions from your address book. It's unclear exactly when it decides to, or rather when it decides not to. It might be related to how many suggestions it was able to find in the nickname list. Regardless, what's important is that entries in your address book are not always presented.

"A little bit of understanding and a few tips will go a long way to making this feature more helpful."

It's frustrating to type the first few characters of someone's name knowing that they're in your address book, but they don't show.

There is a solution.

Press CTRL+K.

Ctrl+K is a shortcut for the "Check Names" button, also on the toolbar when you're composing a message. Check names will look at the characters you've typed so far and compare them to your address book entries. If there's only one match it completes the entry. If there's more than one match then it presents a list for you to choose from. And the list will not include items from the nickname list. But the name you just entered will get added to the nickname list so the next time you use it, it should be there.

Personally, I think it's more confusing than it needs to be. But there it is.

By the way, deleting an address from the nickname list is also very easy: when you see it being suggested use the up or down arrow keys to highlight it, and then press delete.

The nickname list that Outlook maintains can occasionally become corrupt. To repair it or to reset it completely Microsoft has provided this knowledgebase article.

Related:

Article C1939 - May 13, 2004

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Recent Comments
38 Comments

This is a handy freewhere for working with .NK2 files:
http://www.nirsoft.net/utils/outlook_nk2_autocomplete.html

Posted by: Pat at September 2, 2007 12:52 PM

Nice write-up here as well explaining what it is and how to control

http://www.groovypost.com/howto/microsoft/outlook/clear-the-outlook-email-address-auto-complete-cache/

Posted by: MrGroove at January 4, 2008 2:00 PM

dear friends--comcast webmail has had the autocomplete feature, which i actually found very useful. i've just switched laptops & have windows vista (don't know if that's pertinent info or not) & now the autocomplete email address no longer works. i can't get any assistance from comcast--1 person claimed that there has never been any such option. any tho'ts? thanks so much for yr assistance.
holly lu

Posted by: holly lu at January 10, 2008 3:32 PM

When you type first few characters in To Field Outlook suggestions for auto fill (or auto complete) comes from address book or previously sent email.

User can delete auto fill or auto complete suggestison by hitting DELETE key when email address is suggested in To Field

Posted by: Rakesh USA at March 14, 2008 1:09 PM

i am impressed. just fixed my CEO's problem using NK2View v1.23 as he had lost his auto complete list.
it is actually seen as "office data file" not .nk2 in c:\documents and settings\username\application data\microsoft\outlook
it can go both ways by using file--open you can find someone else's other than yours if you are helping someone else. in this case when he saved while not connected to the network it created a new one and he lost them. by renaming the old file to the new name all have back

Posted by: A Carroll at May 28, 2008 11:49 PM

Just an extra tip here for a related problem. My Outlook email started suggesting my full name any time I gave the first name. This makes it quite annoying when you sign as yourself or 'Uncle Carson' and get Uncle Carson Hobart. Not anything of my real name of course.

The way to get Outlook to stop suggesting or adding the last name is actually in Word, which is often the editor for Outlook. The name will actually be in Word's AutoText list. Where do you find that, and delete the whole name so it won't be suggested?

Well, you don't find it in Word's Tools:Options. That would be to easy. It's actually under Tools: AutoCorrect Options. Along with about four other ways Word tries to be helpful. You can just find the whole name you want not to be reminded, and delete it from the list.

How does it get on the list? I am pretty sure this occurred because I finally filled in Word's Options:Tools:User Information. Or some other program did it for me.

Mixed opinions here, as I find some amount of automatic function pretty handy, like capitalizing sentences or lists. In fact, there is one Microsoft program I actually think is almost wonderful in many ways, OneNote, and this is one of the helpful things it does. I actually think they wrote and developed OneNote for Bill.

Hope this helps somebody, and sorry to remain anonymous.

Leo, by the way, is also name for a very useful online German-English-French dictionary.

Regards, and thanks for your site and what you do on it.

Posted by: Narrleo at August 10, 2008 4:22 PM

Hi there, I have just made a very simple php script that can extract the contents of your autocomplete file, take a look at [page removed - see comments below]

basically you copy and paste the contents of your nk2 file and it will give a list of all your email address's.

hope this is useful to someone.

Shaun

Your intent might be good, but consider: you just asked people to give you the email addresses of all their friends. I'm not saying you're not trust worthy, but how do we really know? I've removed the specific page reference so that people don't blindly give you this sensitive information without thinking about why it'd be such a bad idea to do so.

-Leo

Posted by: Shaun Cowley at August 29, 2008 5:51 AM

Thanks for all the help so far but i have one problem i downloaded the NK2VIEW and it works great for my outlook, but when i use my Office Outlook Web Access how do I delete a contact as I Typed in contacts with the wrong email addresss and they keep showing up and i'd like to get rid of them as i keep sending emails to address that don't exist.

Thnks for any help you can give me.

For web access it's just the browser's auto-complete that's kicking in, has nothing to do with Outlook. How do I clear my search history in IE 7? has cleanup info for IE. Pay particular attention to "Form Data".
- Leo
18-Dec-2008
Posted by: jonathan furlong at December 18, 2008 5:32 AM

OK...I've found an easy solution for this issue that seems to work well without any third party sofware. Find the .NK2 file in c:\documents and settings\username\application data\microsoft\outlook, rename it to a .bak, then restart outlook. Outlook will then create a NEW .NK2 file, usually Outlook.NK2. Then, delete the NEW Outlook.NK2 file, rename the .bak file to Outlook.NK2, and restart outlook. The addresses should once again autopopulate. I've tried it twice today and it worked both times. If you need to move this file, just move it to the same folder location on the new computer and follow the same procedure. Hope this helps!

Posted by: Andrew at April 1, 2009 7:18 AM

I looked in this good article and comments, but didn't see the answer to my issue, but I may have missed it. Autofill in Outlook presents a problem in that my wife's email comes up first in the autofill, and if I am not careful, I use it instead of my address. I cc'ed I thought myself on a message, and it went to my wife. Is there a way to "trick" autofill to put my name and address first? I tried adding my email address to a second contact, called "Me." Alas, autofill then prompted last names starting with M, and mine starts with R.

Posted by: AGR at June 25, 2009 1:17 PM

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