I've sold and deployed Barracuda spam and web filters for years. I've always thought that the functionality was good (Barracuda Central, easy interface, effective filtering), but the hardware on the entry to midrange units is a weak point. They have single power supplies, no RAID and limited monitoring support. Personally, I think Barracuda would make a killing selling their software as a VMWare appliance.
I'm looking for something similar that I can deploy as a consultant, but will be easy for customers to manage. It should have support for server-grade hardware or the ability to be deployed as a virtual machine. Is there anything out there that's close?