Design Email Infrastructure for global users
Last updated: October 15, 2025
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
October 15, 2025Software Engineer
Onsite
System Design
Medium
7
10
3,935 solved
Design a high-throughput email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Oracle typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
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
Database selection and data modeling
Failure handling and fault tolerance
Caching strategies (local, distributed, CDN)
Requirements gathering and capacity estimation
Security and authentication
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 would you handle schema migrations with zero downtime?
- How would you handle a 10x increase in traffic overnight?
- What would the deployment pipeline look like for this system?
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Requirements
Functional Requirements
- User Registration and Authentication: Users should be able to create accounts and log in securely.
- Email Sending/Receiving: Users must send and receive emails...
Capacity Estimation
Assumptions
- User Base: 10 million active users.
- Email Volume: Each user sends/receives an average of 50 emails per day.
- Peak Load: Assume 25% of emails are sent during peak hours...
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