Mail Storage Guard 1.2.2
This is an extension for Microsoft Exchange 2000/5.5 and IIS SMTP servers, designed to protect your mail server from spam.
It also prevents mail relaying, mail bomb and NDR attacks. It supports extended blacklists with wildcards; public DNS blacklists (ORDB, SPEWS, SPAMCOP and others); and can reject all "misaddressed" mail (recipient not listed in Active Directory) at SMTP level or point its to postmaster.
Software Breaking News: Google Sync upgraded to provide view it
You can effectively screen calls using Antair Call Screener view it
Challenge/Response systems are quite effective against spam view it