Which MDCA roles will get email notifications by default in Defender for Cloud Apps?

Hi Experts, 

We've recently setup Defender for Cloud Apps but none of the accounts receive email alerts (some of these accounts have associated mailboxes - Security admin, Cloud App Security Admin etc..). 

My questions are: 

How do we setup alerts for admins those who doesn't have mailbox associated to their admin accounts? 

Which roles will natively receive email alerts for default policies? or is it not based on roles? 

This is a grey area in MDCA for me and really appreciate any inputs you may have!. 

Thanks,

Kev