According to the reports of SamMobile.com, T-Mobile has ready to start rolling out Android 6.0 Marshmallow update of Samsung Galaxy Note 5. The update is available over the air and it has 1420MB size for downloading, So please make sure download it by Wi-fi.
New update will delete funcation of per-loaded apps like: Facebook messenger, whatsapp and Instagram.
If you are users of T-Mobile Samsung Galaxy Note 5. So please check out your update of following way Settings -> About Device -> Software update and make sure that bundle is ready for you. If it has not ready for you. so please wait for some time and latest Marshmallow will come on their Galaxy Note 5 soon.