Design an Email Campaign Delivery System
Last updated: October 30, 2025
Quick Overview
Design a system like Mailchimp that enables businesses to create, schedule, and send marketing email campaigns to millions of subscribers with analytics tracking.
Intuit
October 30, 202515
11
4,930 solved
Design a system like Mailchimp that enables businesses to create, schedule, and send marketing email campaigns to millions of subscribers with analytics tracking.
Relevant for Mailchimp teams. Focuses on high-throughput message delivery, ISP rate limiting, deliverability optimization, and real-time analytics at scale.
What the Interviewer Expects
- Design for sending billions of emails with high deliverability rates
- Handle ISP-specific rate limiting and reputation management
- Support campaign scheduling, A/B testing, and segmented audiences
- Implement real-time open/click tracking and analytics dashboards
- Address bounce handling, unsubscribe compliance (CAN-SPAM, GDPR), and spam prevention
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 situation where a major ISP starts throttling your sending IP?
- How do you prevent a single bad actor from damaging sending reputation for all customers?
- What is your strategy for warming up new IP addresses?
- How would you implement predictive send-time optimization?
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Practice System Design ProblemsSample Answer
Sending Architecture
Use a multi-stage pipeline: Campaign Creation, Audience Resolution, Message Rendering, and Delivery Queue. The delivery layer manages a pool of sendin...
Deliverability Management
Maintain per-IP and per-domain reputation scores. Implement automated IP warming for new addresses (start at 100 emails/day, ramp gradually). Monitor ...
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