I was just wondering if anyone here has used any spam blocking software in conjuction with exchange 2000. Apparently it's not good enough for the higher ups to have outlook rules where the spam may flash into their inbox and remain there for a whole 2 or 3 seconds while the rule is processed, it has to be blocked by the server.

So I'm looking into software, and am looking for recommendations. Due to the confidential nature of our e-mail we cannot use any of the off-site filtering solutions.

I've looked into several products, the most effective of which is one where a sender would have to click on a hyperlink in a reply e-mail before their mail is delivered (thus registering them, it happens only on the first e-mail sent to our domain.) However there are concerns with customers being displeased by this approach. Anyway, suggestions? Keep in mind it must work with microsoft exchange, as my old linux pop server did not have all the pretty calender functions these people 'need'.