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

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.

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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.

Do this

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58 comments on “Where do Outlook's auto-complete suggestions come from?”

  1. I cannot seem to find a solution for my out look 2000 from automatically changing the send address to my home email address when I send and email to myself at work.

    Both accounts are brian deller.

    Do you have any suggestions?

    I have window xp pro.

  2. This was helpful — but is there any way to make use of the nickname field when doing something along the lines of auto-completion/check names?

  3. Thanks for your help. I was searching in Outlook Help in deleting nicknames. Actually I didn’t know they were nicknames, I thought they were suggested names. I needed to delete some that were typed in error, and others I didn’t want popping up. You gave me the answer with this

    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.

    Thanks Again,

  4. I’m pleased to find your explanation of the nickname file, and the auto completion function in Outlook. I can’t find this function documented anywhere in the 875-page *Using Outlook 2002* book I’ve been using.

    However, when I use it to find a name in my Contacts file to which I frequently send e-mail, it doesn’t “stick.” That is, I have to Ctrl-K EVERY time. Even though I send e-mail to this person FAR more often than any of the auto completion suggestions that come up, this person from my Contacts file never gets added to the nicknames, or is never suggested. What gives? Are names in a Contacts file treated differently than names in an Address Book?

  5. Very good article! Just one more question. What field does Ctrl+K look for. It seems that it only looks for the last name field and ignores the “File As” field. Can this be changed? So that it looks for the File As instead?
    Thanks again

  6. Until today, I had no problem with my the autocomplete function in my Outlook 2002. Today, I suddenly am not getting and suggestions for names as I type email addresses in which has become a problem because I was relying on this function instead of remembering people’s email addresses.

    In Options–>Email Options –> Advanced Email Options the box for “suggest names while completing To, CC, BCC” is still checked. Any clue on what could be wrong?

  7. Usually it happens because you logged in as a different user, OR opened up a different profile in Outlook. Also, registry cleaners and/or provacy tools can also clean this information out. I’ve not heard of it disappearing on it’s own.

    My recommendation is that you keep addresses you care about in your contacts … that way they don’t disappear.

  8. Thanks!! Every time I typed a colleague’s name in the Send: field, it would choose their home email address first, and I couldn’t find these in any of my address books. I googled for “******* outlook” but that didn’t help.

    Your tip about the “nickname list” and the DELETE button saved my monitor from an untimely end!

  9. The simplest way to solve the “auto-complete” issue is: disconnect the PC from the Internet, open Outlook (I have tested it on Outlook 2003), send an email to all people in Contacts (you may send Bcc), the message will be placed in Outbox folder, close Outlook, open again and go to Outbox, delete the message, you just got your “auto-complete” feature back and working. Regards

  10. Very concise, informative article. I installed the trial version of of Ingressor v3 Desktop on my Win2kPro desktop and it says it cannot find ther .NK2 file in:
    %UserProfile%\Applications\Microsoft\Outlook. I checked the folder security settings and loked myself and it is not there; so… how do I get my NK2 file back?

    Files in folder are:
    MS Outlook Internet Settings.FAV
    MS Outlook Internet Settings.Nick (Huh?)
    MS Outlook Internet Settings.RWZ

    Thank you for any input. Tom

  11. Thank you for the article it was very helpfull. My problem was that I wanted the autocomplete option to always bring up the contacts first and then my ldap address book second. However, I found out that autocomplete brings up the last email you used to send an email to. IE if I used a account and then a account for the same person it would remember the last one I used first and then the yahoo email address second. I could not get them to reorder.


  12. It varies, but the most common situation is logging in to windows as a different user, or selecting a different profile when starting Outlook.

  13. I found that if you use Microsoft’s suggestion to “reset” the nickname file by renaming it, my Outlook failed to create a new one! The nicknames would only be stored in cache and thus be lost everytime I closed Outlook.

  14. I have a problem that many others have listed that I have not seen an answer to. Perhaps there is not one. The nickname list cache disappears each time I close and reopen Outlook. Then I have to start all over repopulating the nickname list.

    I understand one problem can be loggin on as a different user. But I am not logging on as a different user, etc. Any suggestions?

  15. I think I have the answer to my own question. See above for my question. My problem is that I was upgrading Outlook to 2003 from a prior version. Apparently it tries to use the old .nick file. You have to go find it and change the extension. Mine was at C:/DocsSettings/default/Application Data/Microsoft/Outlook. But at least in XP, the .nick doesn’t show and I don’t know how to change the extension. So, I just moved it completely.

    Next, open outlook and chose the repair function. After it runs, close and then reboot. Mine seems to be working fine now and even when I close outlook and reopen, the nickname list still works and I don’t have to start over repopulating.

    Hope this works for you too.


  16. So start an email, type start typing an address and it’ll try to match to your recent cache. Highlight the one in the list that you want to remove (use the arrow keys) then do a shift+delete. Restart outlook, try typing that name again, the one you removed should not reappear.

  17. Hi,

    We use Outlook 2003 (up to date)with Exchange 2003 SP1. When you are typing a name in the TO field and you push CTRL+M, Outlook searches the address book. I think it searches only by last name. I want it to also search for the first name. Is this possible?
    I just read you didn`t know the answer a year ago, I hope you do now. Thanks!


  18. We use outlook 2003 and exchange server / SBS2003. I renamed user Angela in exchangeserver to Maria von Trapp. Now it displays the new user BUT between brakets still the old username in the nicknamelist. Deleting this name and re-entering it, doesn’t delete the old name.

    It looks like:

    Maria von Trapp

    Where comes the ANGELA from? Should be MARIA.

    Thanks! Aernoud

  19. I HAVE DISCOVERED A WAY TO ADD EMAIL ADDRESSES TO THE AUTOCOMPLETE LIST!!! Using the calendar function within Outlook, schedule a meeting and invite others to the meeting. Once you send this meeting request, all invitees will be added to your autocomplete list!!!


    Draft New Email
    In the To: field, type the last name of the person.
    Click outside the To: box and wait until a squiggly red line appears under the name.
    Right click the red squiggly line and select the correct person.
    Close the email. (You do not need to send)
    Note: THis may only work with your network emails)

  21. You can’t find the outlook.NK2 file because you need to tell windows explorer to “Show hidden and system file”. GOOGLE that and you should be able to locate it as the hidden folders and files will become visible.

    Peace out Mr. Baker

  22. 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

  23. 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

  24. 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 settingsusernameapplication datamicrosoftoutlook
    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

  25. 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.

  26. 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.


    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.


  27. 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
  28. 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!

  29. 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.

  30. I have a question. I know how to find the outlook.nk2 file and how to reset. But my issue little different. Some how my automatic Completion Cache reset itself and unable to bring any email or nickname. I send email to couple of email typing whole address, now size is 259K. I try to reset and after reset take this file on the top of new file same thing. Is there any way my (I guess) old outlook.nk2 file to recover? My wild guess would be corrupted may be. Or I read some software install may cause this problem too. It had happen to me before few times and I had to start over from scratch. I wish I knew this outlook.nk2 file name before this time so I could keep backup. Any help will be appreciated. Not sure it auto ctreate any backup of outlook.nk2 file where I can recover aqll my email.

  31. This worked fine on my laptop however, it doesn’t apply at work. I support a network of 60 Windows XP Pro PCs connected to a Windows server 2003 R2 server. None of these PCs have any .NK2 files on them. So where is the autocomplete data being stored? I need to downgrade a user from vista to XP but need to keep the autocomplete info.

  32. Thank you so much! After a recent crash I reinstallaed my contacts list but didn’t know to find or keep the nickname list. Control K works great and will simplify rebuilding it!

  33. Hi slight problem, i have noticed that my name in the autocomplete feature in Outlook’s To field is showing up incorrect in the brackets….
    When i start to type my name it shows the correct email address, but on the right of the email address in brackets it contains my name, which has the incorrect spelling of it, how can i correct this? where would i need to change it?

  34. Wow this worked! I had looked all over the web for a solution and most had me doing very complicated things to the nk2 file which I could not find in windows 7. Thanks.

  35. How put google ads on your comment page? can you share your knowledge

    Just like any other page. I guess I’m not understanding the question.


  36. Why does Outlook try to suggest the fax number in addition to the email address of the person in my contacts listing? I do not have the fax service set, and after doing the check names, have to select which (email or fax) to use. Annoying.

  37. Still not clear where the auto-complete email addresses come from (location), how you can take a backup of these, and how you can re-configure the same in a formated or new machine where you import the earlier MS Outlook mails.
    Also, the above article does suggest that new entries (in to, cc, bcc, from) are not to be found in the adress book; Why is that so? Is there any way to ensure auto-entry or addition of these auto-complete suggestions to the Outlook Address Book or Contacts?

  38. Still not clear where the auto-complete email addresses come from (location), how you can take a backup of these, and how you can re-configure the same in a formated or new machine where you import the earlier MS Outlook mails.
    Also, the above article does suggest that new entries (in to, cc, bcc, from) are not to be found in the adress book; Why is that so? Is there any way to ensure auto-entry or addition of these auto-complete suggestions to the Outlook Address Book or Contacts?

  39. I have clicked the link above but it’s an error, is there other link aside from that?

    All the links above (you didn’t say WHICH link) work for me.


  40. leave it to Microsofdt to make OUTLOOK suck more than the free Outlook Express which did auto complete perfectly- OUTLOOK is way too complicated for no benefit to the user
    – sizing images is now a chore too

  41. Thank you to the person who put this on the comments – THIS WORKS!!!!!
    The simplest way to solve the “auto-complete” issue is: disconnect the PC from the Internet, open Outlook (I have tested it on Outlook 2003), send an email to all people in Contacts (you may send Bcc), the message will be placed in Outbox folder, close Outlook, open again and go to Outbox, delete the message, you just got your “auto-complete” feature back and working.

  42. For the more daring ones among you:
    NirSoft provides a viewer and editor program to manage your list: NK2View and NK2Edit.
    This can be very handy when you want to move your list to a new computer.

  43. Great article. I knew about the CTRL+K but I am still having trouble figuring out why outlook will place the tick marks ‘ ‘ around some email addresses and not others. The problem is that it makes finding an old email address difficult b/c is sorts them independently. Got any suggestions? Can this be turned off?

  44. click a new mail,select the to filed and select the all address in the address book.add them and then save it in your draft.Don’t delete in future.
    the auto completion is now available in your outlook

  45. Thanks, This has been bugging me for so long! Finally I got round to googling the problem. Great, clear advice. Worked first pop.

  46. Thanks for a great little article. I’ve been looking for this information for 3 years, and this is the first article I’ve found that presents a clear and accurate answer.

  47. Speaking of the autocomplete features, I’m having another issue in Outlook with a different autocomplete. Namely the autocomplete in a Meeting Request Location field.

    When you create a meeting there is a Location field in which you enter location information. Next to that field is a drop down error, which contains saved Location information which you can scroll through and change. Then when you save the entry everyone else gets the update with whatever entry you’ve set.

    Is there any possible way to clear all that info so that field is blank? Is there a cache file for that? Will turning off cache in outlook remove this info?

  48. Hi Leo,

    Further to your article, I was wondering how to input someone’s nickname vs. the name they have entered in their Outlook? For example, Terri instead of Theresa. She doesn’t go by Theresa, and I’ve replaced all Theresas in the Outlook Properties fields, but it will only autosuggest if I type “Th” not “Te”….. any way of fixing this?
    When it suggests her name, it still says in the chevrons, but I haven’t found a way of altering what’s in the chevrons. Any ideas?


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