There are several strategies to address this question.
A practical solution is to arrange your emails to be sent to another device other than your phone. This ensures that outside of work hours you are not left with the feeling of ‘always being on’ – a feeling that 46% of Australians say they have because of technology (2016 Snapshot of the Australian Workplace).
If this is not possible then the challenge for you is to be disciplined and avoid the ‘need to know’ syndrome by avoid downloading the full email between say 6:00 PM and 6:00 AM. This may require a conversation with your manager about realistic expectations.
A more extreme measure to achieve work/life harmony is to leave your phone with another person or at the door when you get home.
The greatest challenge is to recognise ‘what’ and ‘who’ are ‘really’ important. If you can answer this question then the work/life balance question is easier to address.