Check whether email address exists in particular Active Directory User Group using C#

not to worry i did some reading and came up with a solution

public static bool AuthenticateGroup(string userName, string password, string domain, string groupname)
  {


      if (userName == "" || password == "")
      {
          return false;
      }

      try
      {
          DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain, userName, password);
          DirectorySearcher mySearcher = new DirectorySearcher(entry);
          mySearcher.Filter = "(&(objectClass=user)(|(cn=" + userName + ")(sAMAccountName=" + userName + ")))";
          SearchResult result = mySearcher.FindOne();

          foreach (string GroupPath in result.Properties["memberOf"])
          {
              if (GroupPath.Contains(groupname))
              {
                  return true;
              }
          }
      }
      catch (DirectoryServicesCOMException)
      {
      }
      return false;
  }