Notification sender with retry
Design a basic notification sender for an app that needs to send emails (and later SMS) — things like a welcome message, a password reset, or a daily digest. The app should not block while the email is delivered, and a transient failure from the email provider shouldn't lose the notification. Volume is modest, a few thousand sends a day. Cover the components, how the app hands off a notification, and how you handle provider failures.
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.
Clarify4:00 left
Estimate4:00 planned
Design11:30 planned
Deep dive9:30 planned
Failure6:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.