Design Email Infrastructure for real-time analytics

Last updated: April 25, 2026

Quick Overview

Design a distributed email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Postmates
System Design
Software Engineer
Postmates
April 25, 2026
Software Engineer
Onsite
System Design
Medium

45

6

118 solved


Design a distributed email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

This is a common system design question asked during Onsite at Postmates. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. Postmates values engineers who can think about scalability from day one.

What the Interviewer Expects
  • Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
  • Design a scalable architecture with clear component responsibilities
  • Make well-reasoned database and caching decisions with trade-off analysis
  • Address consistency vs availability trade-offs specific to the use case
  • Discuss partitioning strategy, replication, and data modeling
  • Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
API design and rate limiting
Failure handling and fault tolerance
Partitioning and sharding strategies
Caching strategies (local, distributed, CDN)
High-level architecture and component design
Message queues and async processing
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you handle schema migrations with zero downtime?
  • How would you implement rate limiting to protect the system?
  • How do you ensure data consistency across multiple services?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Email Infrastructure for real-time analytics, key functional requirem...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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