Notification, since v2.0.0, started showing severity (following https://access.redhat.com/security/updates/classification) in email. The severity is set in the message they accept (see https://inscope.corp.redhat.com/docs/default/component/notifications-app/user-guide/send-notification/#description-of-the-message-format-and-samples).

Subscription threshold exceeded (over usage) currently shows up as "undefined", because the field is not set in the payload we send to the notification service.

This results in the email containing a "double dash" icon (see attached screenshot), that has no direct meaning. Also the prefix of the email subject will change (e.g. "[MODERATE] Instant notification - Subscription threshold exceeded - Subscriptions usage - Subscription services").

Available severity (and relative icons) are shown here https://www.patternfly.org/component-groups/status-and-state-indicators/severity/

Consider that the current implementation of utilization service from swatch side doesn't make difference based on the entity of the over usage (5% threshold crossed produces the same message as a 100% threshold crossed, except for the actual usage percentage shown in the message).

Acceptance Criteria:

• Define a default severity for the over utilization emails.
• Default severity can be override, so also define the potential severity that the email could have.
• Document the decision.