Hi Kevin. Have you tried the Declude/Message Sniffer combo along with configuring a few reliable RBLs at the SM incoming connection checks level for anti-spam filtering? These 3 things are what 95% of our customers use and they are very very pleased with the results. If you would like to give it a try, let me know and I can explain how to get started. Thanks.
Mail's Best Friend
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Authorized Reseller of Message Sniffer