Handle 429 Rate Limit Responses in Instant-Send Email Endpoint

[Ahmed-Ghanam]

Description

The Altinn Notifications API provides two types of endpoints:

1. Queued notification endpoint – registers notifications (email/SMS/both) for scheduled processing.
2. Instant-send email endpoint – registers notification and sends an email immediately to a single recipient, bypassing the queued notification flow.

The instant-send endpoint does not correctly handle HTTP 429 (Too Many Requests) responses returned by Azure Communication Services (ACS). When ACS enforces rate limits, the endpoint currently fails in a way that is neither predictable nor user-friendly.

Problem

• ACS may return HTTP 429 Too Many Requests when rate limits are exceeded.
• The instant-send endpoint does not validate whether sending is allowed based on data in the notifications.resourcelimitlog table.

Acceptance Criteria

• The instant-send endpoint must not attempt to send emails to ACS when the rate limit has been reached.