How many emails does the average office worker receive per day?

How to get close to this number

Think in terms of a working day. Eight hours is 480 minutes; if a message arrives every four minutes or so, that is around 120 a day. Estimating an arrival rate and multiplying by the length of the day is more reliable than guessing the total, and it immediately makes the number feel plausible rather than exaggerated.

Most of it is not correspondence, which is the part people miss. The count includes automated notifications, calendar updates, tickets, copied threads and mailing lists — anything that lands in the inbox. Someone estimating from "how many emails do I actually reply to" will be an order of magnitude low, because reply volume and receipt volume are completely different quantities.

The arithmetic in the explanation is the uncomfortable part. If refocusing after an interruption takes twenty minutes and a message arrives every few minutes, then an unmanaged inbox consumes more attention than a working day contains. That is the actual finding behind the statistic, and it is why the number is quoted in productivity research rather than in technology reporting.