Microsoft has been selling Forefront (the commercial version of Security Essentials/Defender) since 2007[0], 2 years before Security Essentials was released. [

Microsoft has been selling Forefront (the commercial version of Security Essentials/Defender) since 2007[0], 2 years before Security Essentials was released. [0]: It's hard to track down a specific date since they've been going through a bunch of rebrands, but https://www.csoonline.com/article/545304/cisco-subnet-whatever-happened-to-microsoft-forefront-endpoint-protection.html https://www.csoonline.com/article/545304/cisco-subnet-whatev... seems like the earliest date I can find, with a bunch of other sources from 2009 talking about new updates.