Security ramifications, in addition to the Outlook dependency left me unable to use this approach, in the past. As a result, I ended up building this in the form of an LDAP query. Another plus is that, (in response to your other question) you will be able to extract contact information because this information is stored in the Active Directory.
DISCLAIMER: It has been almost five years since I have looked at this code, so I m afraid I no longer fully understand the query. Hopefully it s enough to get you started, however.
DirectoryEntry adFolderObject = new DirectoryEntry();
DirectorySearcher adSearcher = new DirectorySearcher(adFolderObject);
adSearcher.SearchScope = SearchScope.Subtree;
adSearcher.Filter = "(& (mailnickname=*) (| (&(objectCategory=person)(objectClass=user)(!(homeMDB=*))(!(msExchHomeServerName=*)))(&(objectCategory=person)(objectClass=user)(|(homeMDB=*)(msExchHomeServerName=*))) ))";
foreach (SearchResult adObject in adSearcher.FindAll())
{
Console.WriteLine("CN={0}, Path={1}", adObject.Properties["CN"][0], adObject.Path);
}