Corrupt Exchange AutoComplete

So this has happened to me twice and I had forgotten how to fix (‘fix’) it from before so I’m writing it down here for when I inevitably forget again.

The symptom is that the user’s address autofill/AutoComplete within Outlook stops working. Since we run on a later version of Exchange this means that the autofill information that is stored on the server is corrupt (this post applies specifically to Outlook 2010/Exchange 2013). As far as I can tell the settings on the server are gone so the information has to be reconstructed, which for the user, is better than nothing. To do so I follow these easy steps:

  1. Download NK2Edit
  2. If you want a backup of the corrupt information, you can follow the steps here or backup the ‘DAT’ files (outlined in this post, though there seems to be a consensus that this won’t do the trick on Exchange where these files are always ‘pushed’ and never ‘pulled’)*.
  3. Clear out the existing AutoComplete (Step 4 here under “let me do this myself”)
  4. Open NK2Edit and make a new NK2 file with the same name as the Outlook profile (typically ‘Outlook’).
  5. Click the add button within NK2Edit and add every address that you can get your sticky fingers on, especially the addresses under ‘suggested contacts’.
  6. Exit Outlook and put the NK2 file in the proper path and go to Start->Run->outlook.exe /importnk2

Other suggestions:

  1. This article suggests the command ‘/CleanAutoCompleteCache’, but this would only seem to apply if there was a problem with the single Outlook install.
  2. One could always (*ugh*) restore the mailbox from an earlier time, etc., etc. I would reserve that course of action only for drastically desperate situations.

*I came by this tip ( which says that you may be able to restore autocomplete entries with the cache file by using the MFCMAPI tool.  The caveat is added since the procedure basically involves hacking the mailbox so some risk is involved.

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