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
August 15, 2025198
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
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- 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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Requirements
Functional Requirements:
- User Authentication: Allow users to sign in using Salesforce credentials.
- Email Sending: Provide APIs for sending emails in real-time, with support for attac...
Capacity Estimation
Back-of-Envelope Calculations:
Assuming Salesforce has approximately 100 million users, and each user sends an average of 10 emails per day:
- Total Emails Per Day: 100 million users * 10 emai...
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