Design Email Infrastructure for microservices
Last updated: May 4, 2026
Quick Overview
Design a multi-tenant email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Elastic
May 4, 20265
6
146 solved
Design a multi-tenant email system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Elastic asks this during the System Design Round to assess your understanding of the full ML lifecycle. They want to see how you translate a business problem into an ML objective, design the feature pipeline, and plan for model monitoring and retraining.
What the Interviewer Expects
- Design the full ML lifecycle from data collection to model monitoring
- Address cold start, exploration/exploitation, and model freshness
- Discuss multi-objective optimization and ranking systems
- Plan for model debugging, fairness, and bias mitigation
- Design the feature store and training pipeline for scale
- Address model versioning, canary deployments, and rollback strategies
- Discuss the data flywheel and long-term system evolution
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
- How would you handle a 10x increase in prediction requests?
- How would you run A/B tests on different model versions?
- How would you handle the cold start problem?
- How would you ensure fairness and reduce bias in the model?
Practice a Similar Problem on Codemia
Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.
Solve on CodemiaSample Answer
Requirements
Functional Requirements
- Multi-tenancy Support: The system must support multiple organizations with isolated email data and configurations.
- Email Sending/Receiving: Users should be ab...
Capacity Estimation
Assuming Elastic has around 1 million users, with an average of 50 emails sent and received per day:
- Daily Email Transactions: 1,000,000 users * 50 emails = 50,000,000 emails/day.
- **Per Secon...
Submit Your Answer
