Hi. Yes you can handle all those use cases in my app eNotify. It has a lot the same support that BlackBerry tier 1 had. It is designed for people that work on-call or have high volumes of email.
For your use case:
1. Setup your account(s)
2. Create an alert with a 'trigger' of {Sender, Subject or Priority} depending on what you want to accomplish
3. Choose an individual sound for your alert
4. Set 'Override Silent' to ON -> This overrides the phone's silent profile
5. Set the 'Override Volume' as you want -> You can override silent with a quiet sound or loud one
There is a free version of the app here. It doesn't have any real restrictions as such:
https://forums.androidcentral.com/e?...token=DqYj3wXC
Regards,
Glen