System designEasysd-g551

Subject QueueingLevel Entry–Mid~30 minCommon in Algorithms & data structures interviewsIndustries Software development, Technology

Question

Design a simple background job/queue for sending emails in a small SaaS app (signup confirmations, password resets, notifications). When something triggers an email, the web request should return immediately rather than waiting on the mail provider. Volume is a few thousand emails a day. Describe how a job gets enqueued, processed, and what happens when sending fails.

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.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.