Estimating Gmail's Inbound Email Volume per Second

Estimate how many email messages Gmail receives per second. ```hint Pin down what one message is Decide early whether an email sent to five Gmail users counts once or five times, and whether filtered spam counts. Then ask where most of the mail landing in an inbox actually comes from. ``` ### Clarifying Questions - If one email is addressed to several Gmail users, does it count once, or once for each recipient's mailbox? - Should spam that Gmail filters or rejects count, or only mail delivered to users' inboxes and folders? - Should work and school accounts count, or only personal accounts? - Do you want the average rate across a day, the peak rate, or both? ### What a Strong Answer Covers - A precise definition of a received message, agreed before any numbers appear - A clear equation built from active accounts and messages received per account, segmented by account type or usage level - Round assumptions, each labeled, and correct arithmetic carried through to a per-second figure - The step from an average to a peak rate, and how including spam changes the number - A sanity check against an independent reference point, and which assumption moves the answer most ### Follow-up Questions - How does your estimate change if an email sent to several Gmail users counts only once? - If you were sizing Gmail's inbound mail servers, which figure would you plan around, and why? - Which assumption would you validate first, and how?