Are you talking about contacts stored in Active Directory or contacts stored
in a public folder or mailbox?
If you talking AD contacts then you can use LDAP and System.DirectoryService
namespace in VB.NET or if your talking contacts stored in a mailbox or
public folder then you can use WebDAV and the System.NET namespace in
The best place to start with programing referances and samples is the
Exchange SDK which you can download from http://www.yqcomputer.com/
there are plenty of .NET samples in there.