Design a large-scale Email Platform

Last updated: August 15, 2025

Quick Overview

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

Salesforce
System Design
Software Engineer
Salesforce
August 15, 2025
Software Engineer
Technical Screen
System Design
Easy

198

5

2,860 solved


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

This is a common system design question asked during Technical Screen at Salesforce. 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. Salesforce values engineers who can think about scalability from day one.

What the Interviewer Expects
  • Clearly define functional and non-functional requirements
  • Propose a reasonable high-level architecture with core components
  • Choose appropriate data storage solutions with basic justification
  • Discuss basic scaling strategies (horizontal scaling, caching)
  • Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
API design and rate limiting
Load balancing and horizontal scaling
Partitioning and sharding strategies
Consistency models and replication
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
  • What happens if one of your database nodes goes down?
  • How would you optimize costs as the system scales?
  • How would you migrate from a monolithic to a microservices architecture?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For large-scale Email Platform, key functional requirements include: what...

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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