Step 1 of 13 · Intro

Design an email service

Send, receive, search, and never lose a message.

How it works

• ›Receive: accept mail fast, store it, index it for search.
• ›Search: query an index instead of scanning every message.

What you'll build

1. The API and the data behind it
2. A server, a database and a search index
3. A queue and workers that absorb a newsletter burst
4. A rate limiter against a spam flood
5. A design that survives a cold cache, a lost index node and a lost primary