Symptoms:
Administrators are unable to configure email notifications from vCenter.

vCenter > Configure > General > Mail the option is grayed out.

This feature is unsupported in VMC SDDCs.

Workaround:
Alerts related to vCenter like host CPU and memory usage or virtual machine snapshot size are not sent through email notifications. This feature is not available in VMC vCenter. Users will be able to see these alerts under the Activity Log of the VMC vCenter.

VMware notifies users in cases where the engineering team has taken certain proactive steps for user's environment. Please review the following document for a comprehensive list of alerts VMware teams will alert you with https://docs.vmware.com/en/VMware-Cloud-on-AWS/services/com.vmware.vmc-aws-operations/GUID-1DD2D320-B9E0-409E-B579-053DBA5299F5.html

Alerts are sent out to all the organization owners and users.