Hello, welcome to the forums!
Which email app are you using? In Gmail go to settings - tap on the account - uncheck the notifications box. Also, you can manage the notifications for each label/folder individually. To do this tap on the "manage labels" option in the same settings screen.
If you want to keep the notifications and just remove the sound you can select "none" after taping on the sound option. In this case remember to keep the notifications box checked. The same applies for your different accounts and labels.