In case you are not aware, Google is having their big developer's party with Google I/O for the next few days.  It is expected that Android N will be announced, which means that pretty much all Android device manufacturers really should have been upgraded with Android M (otherwise known as Marshmallow or version 6.0) by now.  This is the latest news on Android M 6.0 Marshmallow Release Date for HTC One M9, One M8, and HTC Desire Series on Sprint, US Cellular, Verizon, T-Mobile, and AT&T. 

One of the issues with Android rollouts is that they can be quite slow, and there often isn't any difference in one week of reporting it to the next.  This is not the case this week, as AT&T finally has received its upgrade on the HTC One M8 and the HTC One M9.  This is according to Android Authority, who has the word from Mo Versi. 

If you are not familiar with Mo Versi, he is the Vice President of Product Management at HTC.  He is generally the guy that brings the word about whether or not the latest version of Android is available to HTC.  With AT&T out of the way, that makes all of the carriers including Verizon, AT&T, US Cellular, and T-Mobile covered. 

So, that means that both of the flagships from the past two years are covered, with no plans for the M7, the flagship from three years ago, to receive it.  This comes just in time as the HTC 10 (name changed for simplicity) has begun to come rolling out, and it has so far received some positive reviews. 

So, that goes for the flagships, but what about other phones under the HTC umbrella like HTC one M9+, HTC One E9, HTC One ME, HTC One E8, HTC One M8 EYE, HTC Butterfly 3, HTC Desire 826, HTC Desire 820, and HTC Desire 816, as well as the One A9, Desire Eye, and One E9?  A separate report from Android Authority states that the Marshmallow rollout is on its way for these devices, but there really hasn't been any word on when.

The safest bet is that if you have a recent HTC device, you might already have access to Marshmallow already, especially if you have a flagship.  Just go to "Settings" and "System Update" to see if you can download the Over the Air (OTA) upgrade now.  It is possible that the upgrade could be available on one carrier for the same phone and yet not on another, which has become a pattern for Android rollouts.