Completely confusing isn't it. Especially when you are a customer that doesn't receive any notification of name changes, product reassignments, etc. I've been a symantec volume licensed customer for over a decade, and I'm more confused by their naming standard, product families, and licensing structure, than ever before.
To answer you question, the SAV for SMTP for Windows product was replaced with Symantec Brightmail Gateway. It comes as an appliance, or an ISO that can be used to automatically build up a VM under an ESX or ESXi box. These VM's are built off of a Linux kernel, so there is no Windows version.
I've made the change over the past few weeks, and am very pleased with the new product. I found it ironic though that Symantec went from a "don't you dare even try to virtualize SAV for SMTP" to "oh, the replacement product can be an ESX VM only, and by the way, the end of life was just announced for our old product. ...have a nice day." Okay, so that isn't exactly what Symantec said, but that is the impression that a long time customer (me) got.