I to have got the same issue with gmail push Notification on s6 edge plus
Solution 1 : Settings - > Apps -> : (Three dots on the Right Top ) -> select -> special access -> optimise battery usage -> Select all Apps (Drop down ) Turn off -> gmail
This will not Give the Push Notification but it will give the Email sync already you open the Gmail app
Solution 2 : Download the Inbox App by google and then do the same above steps in the optimise battery
This will give you the Push Notifications
Solution 1 : Settings - > Apps -> : (Three dots on the Right Top ) -> select -> special access -> optimise battery usage -> Select all Apps (Drop down ) Turn off -> gmail
This will not Give the Push Notification but it will give the Email sync already you open the Gmail app
Solution 2 : Download the Inbox App by google and then do the same above steps in the optimise battery
This will give you the Push Notifications
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