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2 articles tagged email.
HLDintermediatePremium
Gmail HLD: Storing Billions of Mailboxes and Threading Conversations
How an email service works inside: accept-fast ingestion, the shared message store plus per-user mailbox index, conversation threading by reply headers with union-find, and per-user search.
9 min read
HLDintermediate
Newsletter Service HLD: Fan Out a Million Emails Without Sending Twice
A newsletter service system design: fan a campaign out to millions of subscribers, the send-log idempotency key that stops double-sends, plus deliverability, retries, and open/click tracking.
14 min read