Design a Marketing Email System
Company: StubHub
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
Design a marketing email system for a ticket marketplace.
The business wants to run marketing campaigns that send 2 to 3 emails during a configured 15-minute delivery window. The system must support users across multiple time zones and must measure both delivery success and downstream conversion.
Cover the following areas:
1. How campaigns are created, scheduled, and executed.
2. How to handle time zones correctly, including daylight saving time and users with missing or invalid time zone data.
3. How to send 2 to 3 emails within a 15-minute window while respecting provider limits, retries, idempotency, and user frequency caps.
4. How to run A/B tests across different email subjects, templates, send times, or recommendation strategies.
5. How to track whether an email was sent, delivered, bounced, opened, clicked, unsubscribed from, or converted into a ticket purchase.
6. How to attribute conversions to email campaigns.
7. How to monitor reliability, latency, and experiment results.
Quick Answer: This question evaluates system design and engineering competencies for building a scalable, reliable marketing email platform, covering scheduling, time zone handling, delivery constraints, A/B testing, event tracking, conversion attribution, and monitoring.