Sharepoint not getting current user NetworkCredential from active directory - asp.net

Question

we have strange problem, we have single signon and we are trying to fetch unread email count from Exchange ews webservice, the problem is it always gets same count for all user which is actually for server user.
'it should now get for current user who requested the page
'but its always for server user where sharepoint is installed
Public Sub GetUnreadEmailCount()
Dim errormsg As String = String.Empty
Dim UnreadCount As Integer = 0
Dim esb As New ExchangeServiceBinding
Try
esb.RequestServerVersionValue = New RequestServerVersion
esb.RequestServerVersionValue.Version = ExchangeVersionType.Exchange2007_SP1
esb.UseDefaultCredentials = True
esb.Url = Domain + "/EWS/Exchange.asmx"
ServicePointManager.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf CertificateValidationCallBack)
Dim biArray(1) As BaseFolderIdType
Dim dfFolder As New DistinguishedFolderIdType
dfFolder.Id = DistinguishedFolderIdNameType.inbox
biArray(0) = dfFolder
Dim geGetFolder As New GetFolderType
geGetFolder.FolderIds = biArray
geGetFolder.FolderShape = New FolderResponseShapeType
geGetFolder.FolderShape.BaseShape = DefaultShapeNamesType.AllProperties
Dim gfResponse As GetFolderResponseType = esb.GetFolder(geGetFolder)
Dim rmta As ResponseMessageType() = gfResponse.ResponseMessages.Items
Dim rmt As FolderInfoResponseMessageType = DirectCast(rmta(0), FolderInfoResponseMessageType)
If rmt.ResponseClass = ResponseClassType.Success Then
Dim folder As FolderType = DirectCast(rmt.Folders(0), FolderType)
UnreadCount = folder.UnreadCount
End If
Label1.Text = vbCrLf + "Unread email count : " + UnreadCount.ToString
' Return UnreadCount
Catch ex As Exception
If Not ex.Message Is Nothing Then errormsg = ex.Message
Try
If Not ex.InnerException.Message Is Nothing Then errormsg = errormsg + " : " + ex.InnerException.Message
Catch e As Exception
End Try
Finally
If esb IsNot Nothing Then esb.Dispose() : esb = Nothing
If Not errormsg = String.Empty Then
Label1.Text = vbCrLf + "Error : " + errormsg
End If
End Try
End Sub

Answer 1

We were actually having the same problem, although we were not using single sign on. So I'm not sure this is exactly what you are experiencing.
The problem is that you can not have a user on Machine A give their credentials to Machine B (SharePoint?) and then have Machine B send those credentials on to Machine C
It's referred to as the "Double Hop" problem and is a security feature, however I'm not really into the technical side of it. Our solution was to use Kerberos.
I hope this helps you, if not, that it helps you rule out this specific issue :)

Answer 2

Your server side code is running as the AppPool's identity, which is your sharepoint service account. I'm assuming that's what you mean by 'the server user.'
esb.UseDefaultCredentials = true;
will use the creds of the context. I'm not sure of what's available in the EWS services, so if you can use a higher-privileged account and get based on the user coming in, i.e., HttpContext.Current.User.Identity as a parameter, then that may be the best way.
You could authenticate via javascript directly to the EWS services, skipping server-side code altogether, and write something that consumes & displays the server stuff as you need it.
You'd need to find a way to auth the user directly to the EWS services. Double-hop is an issue with NTLM, as your NTLM ticket is only valid for the first hop. Kerberos fixes that, but you still need to impersonate.