The $15 Inbox
On paper, sorting a shared inbox of 1,000 emails a month with AI (reading, classifying, routing and drafting replies) costs about $15 a month. The software is cheap; the work is deciding which emails still reach a person.
Sorting a shared inbox of 1,000 emails a month with AI (reading, classifying, routing and drafting replies) works out at about $15 a month in total. At that price, the only real question is which emails still need a person.
The $15 is arithmetic for a hypothetical inbox, not a bill, and it rests on one assumption to challenge first: that 60% of emails match one the system has already handled.
What Email Costs a Team Now
In a 2012 study, McKinsey found that the average knowledge worker spends 28% of the working week on email, about 2.5 hours a day. For a team of 10 at $30 an hour, that is $195,000 a year (illustrative: 260 working days).
Where the Emails Go
Take a shared client inbox that receives about 50 emails a working day, roughly 1,000 a month. Each one needs a decision: reply, forward, escalate, archive or ignore.
Illustrative: a hypothetical shared inbox of 1,000 emails a month. The mix is an assumption; measure your own.
In this example, 85% of the mail follows a pattern software can handle, and 15% needs a person.
What Each Email Costs to Process
Each email passes through five steps, priced here as rough estimates at the published rates of a small, fast model (Anthropic’s Haiku).
Email Arrives
The mail server passes it on: no model cost
Classify It
The model reads type and urgency: about $0.001
Draft a Reply
The model writes a reply in context: about $0.002
Check Confidence
Send it, or queue it for a person: about $0.001
Remember the Pattern
Stored, so a similar email next time costs almost nothing
An email the system has not seen before costs about $0.004 to process; one that matches a stored pattern costs about $0.00002. At a 60% match rate, 1,000 emails cost about $1.60 in model calls. Hosting and a database add about $13, for a total of about $15 a month.
Why the Cost Falls Over Time
Every email is new to the system and is processed from scratch. Pattern matches: 0%. Model cost: about $4 for 1,000 emails.
Assume 60% of emails now match a pattern the system has already handled; those cost almost nothing. Model cost: about $1.60 for the same 1,000 emails.
Out-of-office replies, appointment confirmations, booking requests and pricing questions should match well. The 60% is our assumption for their share of an inbox; the whole sum moves with it.
What Stays With People
Before anything is built, count one month of your shared inbox: how many emails arrived, and how many followed a pattern your team would recognize. That count decides whether the arithmetic holds for you. The risk is an email that needed a person and never reached one, which is why anything uncertain goes to a person’s queue.
How many emails in your shared inbox follow a pattern?
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