Design a large-scale Email Platform
Last updated: March 23, 2026
Quick Overview
Design a high-throughput email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Oracle
System Design
Software Engineer
Oracle
March 23, 2026Software Engineer
System Design Round
System Design
Medium
1
11
2,794 solved
Design a high-throughput email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Oracle asks this during the System Design Round to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
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
Monitoring, logging, and alerting
Database selection and data modeling
Requirements gathering and capacity estimation
Load balancing and horizontal scaling
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
- How do you ensure data consistency across multiple services?
- What happens if one of your database nodes goes down?
- How would you optimize costs as the system scales?
- How would you implement rate limiting to protect the system?
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Requirements
Functional Requirements
- User Registration & Authentication: Users should be able to create accounts and log in securely.
- Email Sending: Users can send emails to multiple recipients w...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume we aim for 10 million active users.
- Email Volume: If each user sends/receives an average of 10 emails per day, that's 100 million emails...
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