Still using older Windows OS? You won't be able to access Gmail from today

Gmail will continue to function on Chrome Browser v53 and below through the end of the 2017

Those using Windows XP and Windows Vista will not be able to use Gmail starting today. Due to new security measured being implemented in Gmail, the site will only fully load on Chrome versions above Chrome 53, anything versions below will be redirected to a basic HTML version as early as December 2017. Also, these users will not have access to new features and bugfixes.

Gmail will continue to function on Chrome Browser v53 and below through the end of 2017. 

Google in a blog said, "Google does not typically announce when we discontinue support for older versions of Chrome