Motorola has updated its list of devices scheduled to receive Android 6.0 Marshmallow, and a notable addition is the Moto E 2015. When Motorola published the original list in October, the Moto E's omission was quickly noted, particularly because the device went on sale just a few months earlier and the manufacturer promised timely updates.
And although Motorola will roll out the Marshmallow update to the Moto E 2015, it will only be available in select regions, which include Canada, Europe, Latin America, and Asia (excluding China). It doesn't look like the update will be rolled out to customers in the U.S., as Motorola's software upgrade page makes no mention of the Moto E.
Thanks for the tip Ryan!