<?
  $txt = "goragod@yahoo.com";
  $txt = preg_replace('#(.*)\@(.*)\.(.*)#' , '<a href="mailto:\1@\2.\3">Send email</a>',$txt);
  echo $txt;
?>

<?
  $txt = preg_replace("#(^[ ])([a-z0-9&\-_.]+?)@([\w\-]+\.([\w\-\.]+\.)*[\w]+)#i" , "\1<a href=\"mailto:\2@\3\">\2@\3</a>", $txt );
?>