 Sixteen months after the release of version 2 @.@ 0 , Microsoft skipped version 3 @.@ 0 and released Microsoft Security Essentials 4 @.@ 0 . A public beta program started on 18 November 2011 , when Microsoft sent out invitations to potential participants without announcing a version number . The first beta version was released on 29 November 2011 , and the final build on 24 April 2012 . Microsoft subsequently initiated a pre @-@ release program that provides volunteers with the latest beta version and accepts feedback . 
