L4 · Medium
Notification System
Problem
Design a notification service that can send alerts via multiple channels based on user preferences and event types.
Requirements
- Support channels: Email, SMS, Push, In-App
- Users configure preferred channels per notification type
- Priority levels: Low, Medium, High, Critical
- Rate limiting per channel
- Retry failed notifications
- Notification history and read/unread tracking
Constraints
- –Critical notifications bypass rate limits
- –Max 100 emails/hour per user
- –Retry max 3 times with exponential backoff
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