System Design Interview
Email service inspired by Gmail: a mailbox store partitioned by user, sending through a delivery queue with SMTP retries, attachments stored once in object storage, an inbox cache, a per-user search index fed from a mail event stream, spam filtering with SPF, DKIM, DMARC and a classifier, push sync over open connections, and daily send limits. A teaching design.
Build this system yourself on the canvas below. Add components, connect them, and run traffic simulations to see where your design holds up and where it breaks.
You're in the middle of an interview session. Leaving now will end your current attempt.
Explore concept overviews, real-system examples, key tradeoffs, and interview talking points for each roadmap section.
You've conquered this phase. These are the skills you now own:
