I am going to publish spam/phishing that lands in my mail here to help you all to identify and NOT click on any links.
Hurray the new Imac is upgradeable!! Hell has frozen. See the teardown of Imac 21,5" 4k here and check it out "under the hood"!!
Mac OS X Sierras fifth update is out. I have just installed it myself and everything seems to work.
This is a security and bug fix. It should definitely be installed AFTER you are sure you have backup!