Each time that you send a new message in Outlook, the emails that you type in To/Cc fields, are automatically inserted into the AutoComplete list, so in the next time that you type an email address, Outlook automatically completes the right email address for you.
The AutoComplete file of Outlook is stored under [Your Profile]\Application Data\Microsoft\Outlook , and it always saved as the profile name of Outlook with .NK2 extension.
This utility reads the AutoComplete file of Outlook (with .NK2 extension), displays all email records stored in it, and allows you to easily export these records into text/html/xml file.
Download this utility at Nirsoft.net