for($i=0; $i<count($santas); $i++)
   {
      if ($i < count($santas)-1)
      {
         sendEmail($santas[$i]['0'],$santas[$i]['1'],$santas[$i+1]['0']);
      } else {
         sendEmail($santas[$i]['0'],$santas[$i]['1'],$santas['0']['0']);
      }
   }

/*
$santas is a shuffled multidimensional array of persons and their email addresses.
*/