Many email clients will offer an autofill feature that remembers previously used email addresses and fills them in based on what you are typing in the recipient field of your email client. This comes in handy if you want a fast way to enter email addresses without having to use your address book to look up names assuming you know part of the email address so you can start typing it and let the autofill feature complete it for you.
On the other hand Im sure you have noticed that your email client will start to get cluttered with addresses that you don't want there. Perhaps you have email addresses that were used one time and now they constantly show up in your autofill feature.
If you are a Microsoft Outlook user I'm sure you have noticed that when you type an email address into the To: field that Outlook will try and figure out who you want to send your email to by giving you choices from previously used email addresses. You may have also noticed that Outlook saves email addresses that you may have used only once or that you don’t necessarily want to keep.
NK2View is a free utility that allows you to edit the entries in your username.nk2 file where username is the name of your Outlook profile. The .nk2 file is where your email addresses are stored that are used for the autocomplete feature. This is different that the addresses stored in your address book so you don’t have to worry about erasing those on accident.
With NK2View you can delete unwanted email addresses from your autocomplete file and add new addresses from your address book as well as edit current email address entries. You can also print out a report listing all of the entries in your .nk2 file in a web format. One thing you should do before using this program is backup your .nk2 file just in case you delete something on accident that you needed. There is a known issue with the program that if you try and add addresses to your file then it may corrupt your .nk2 file so be careful. If you have a backup you should be fine though.
NK2View is a free download from NirSoft and you can get the software by going to their website here.