Get UPN or email for logged in user in a .NET web application

I have an ASP. NET web application that makes user of the user credentials of the logged in user. Currently it uses the SID which comes from

System.Security.Principal.WindowsIdentity.GetCurrent().User.Value

I need to get either the users UPN login or email address (as defined in active directory) instead of the SID. GetCurrent() returns an object of type WindowsIdentity; looking in the details for WindowsIdentity Members:

http://msdn.microsoft.com/en-us/library/system.security.principal.windowsidentity%5Fmembers.aspx

I can't see anything that looks like it would give me either the UPN or email in there. How can I pull up that information to use, either by feeding the SID into some other function or calling something different in the first place.

System.Security.Principal.WindowsIdentity.GetCurrent().Name returns "DOMAIN\user", so that is not the answer.

DrStalkerAsked:
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HairbrushCommented:
Try this, which requires System.DirectoryServices.


   private string CurrentUserEmail()
   {
		string tempCurrentUserEmail = null;
 
		//Returns the email address of the current user from Active Directory
 
		string sCurrentUser = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
 
		sCurrentUser = sCurrentUser.Substring(sCurrentUser.IndexOf("\\") + 1);
		DirectoryEntry Entry = new DirectoryEntry("LDAP://RootDSE");
		string sFQDN = System.Convert.ToString(Entry.Properties["defaultNamingContext"].Value);
		DirectoryEntry myDE = new DirectoryEntry("LDAP://" + sFQDN);
 
		DirectorySearcher mySearcher = new DirectorySearcher(myDE);
 
		mySearcher.Filter = "sAMAccountName=" + sCurrentUser;
		mySearcher.PropertiesToLoad.Add("Mail");
		try
		{
			SearchResult myresult = mySearcher.FindOne();
			tempCurrentUserEmail = System.Convert.ToString(myresult.Properties["Mail"][0]);
		}
		catch (Exception ex)
		{
			throw new ApplicationException("Could not establish an email address for user " + sCurrentUser);
		}
 
		return tempCurrentUserEmail;
	}

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