Microsoft has reportedly decided to drop the "messaging everywhere' feature in Windows 10's Anniversary edition. The feature sync's messages across all your Windows 10 devices and PCs, similar to what Apple's iMessage and Messages apps have done for years on iOS as well as Mac devices signed into a specific email address.
The feature is supposedly enabled by turning on the "Send texts on all my Windows devices" enabled users to send and receive text messages from the Messaging app on their computer that synced directly with the app on their phone. There's no ETA on when this feature will grace Windows 10 devices.
Source: Engadget