[Admin]

Oh ok I see the problem now, you are coding this the wrong way.

Replace this:

  $useremails=$DB_site->query("SELECT user.*
                               FROM subscribethread,user
                               WHERE subscribethread.threadid='$threadid'
                                 AND subscribethread.userid=user.userid
                                 AND user.userid<>'$userid'
                                 AND user.lastactivity>'$lastposttime[dateline]'");

  $useremails=$DB_site->query("SELECT user.*
                               FROM subscribethread,user
                               WHERE subscribethread.threadid='$threadid'
                                 AND subscribethread.userid=user.userid
                                 AND user.userid<>'$userid'");

And add this:

    if (!$touser['allemail'] and $touser['lastactivity']<=$lastposttime['dateline'])
      continue;

Right after this:

  while ($touser=$DB_site->fetch_array($useremails)) {