We are running exchange 2000. Our SMTP queues are filling up with what looks like spam. We are set up not to relay and from what we've read we are not forwarding these emails but exchange is trying to send out NDR's for these emails but the addresses are probably fake so they sit in our queue for 3 days till they are deleted. The problem is we have 10's of thousands of emails in our queue taking up space. My question is how can we prevent these emails from getting to our queue. Is there some setting in Exchange or do we have to use a 3rd party spam program. Any help would be appreciated.