Android 6.0 includes Doze, which puts an inactive Android phone into a deep sleep in order to increase standby time and improve battery life. The update also changes requests for app permissions, allowing users to give or deny permission on a feature-by-feature basis. And Google Now on Tap offers search responses based on the content on the screen at the time the search request is made.
Besides Sprint, the HTC One M9 will start receiving the Android 6.0 update on Monday for customers of Canadian carriers Sasktel, Rogers, Wind, and Videotron. Once you receive the notification that the update has arrived, before downloading and installing it you need to make sure that you're connected to a Wi-Fi signal. Also, you should make sure that your battery is charged to at least 50%.
HTC's Mo Versi reveals that the Sprint branded HTC One M9 will receive Android 6.0 in the middle of next week
source: @moversi via AndroidCentral