Its bit urgent one!!
we have 1 x exchange 2010 server (which has more then 200 mailboxes) and exchange 2003 (which has no mailboxes but is used as anonymous internal mail relay server) but queues just dont clear quick enough, however restarting the Edge Transport Service gets mail delivered and then after a few minutes the problem comes back!
And if we restart the service it comes back to normal but then a few mins later it slows down again. 2003 server to 2010 we use a send connector.