Spoof emails

Hi,

Does anybody know of a good 3rd party software where I can use to prevent spoof email and drop connection to all non-existence recipient? Our exchange 2000 server receives about 1000 or more a day of ndr to ex employee or to recipient that doesn’t exist. This is not really a big issue but it does put a strain on our bandwidth.

We currently have exchange 2k server with windows 2k server. We also have trendmicro scanmail and emanager for exchange. Any help of suggestions would be appreciated. Thannks!