http://googlesystem.blogspot.com/2014/11/gmail-50-for-android.html?m=1

[THAIPHUKET]

I'm confused, my Gmail stopped and this here says I must have gmail.com 5

[RichCor]

Pretty sure the previous gmail app will still work, as it was just released for general consumption and there are many, many people who have yet to transition.

If you are having issues, make sure you time/date is in sync. SSL connections are a b'tch sometimes.