Share your experience!
are you using preloaded ringtones or your own music?
Where are the music files located?
Hi @MalR, I'm sorry to hear about this. 
If you select another preloaded notification sound, does that work or is it still playing the default notification when you receive an email?
If it still plays the default ringtone I'd recommend that you clear data for the Email application, this will remove any email account(s) you have added in the app so make sure you have the correct information at hand so you can add your account(s) again. To clear the data for the application go to Settings > Apps > Email > Storage > Clear data.
Let me know how it goes! 
Thanks for getting back to me.
I will forward this internally as user feedback.
I'm sorry I couldn't provide you with a working solution. 