Useful agents worth building ยท No. 1
An email agent that writes like you, and gets better every night
About 45 minutes to set up. Then you check drafts instead of writing them.
Three times a day an AI agent goes through my inbox. It clears out the noise, writes replies to the rest in my voice for me to check, and asks me a short question when it needs a steer. Every night it compares what it drafted with what I actually sent, works out what I changed, and updates its own rules. The longer it runs, the less I edit.
This free guide gives you the steps and the copy-and-paste prompts to build your own. It starts where it should: teaching the agent how you write.
- 45 minutes to set up
- 3 sweeps a day
- Learns every night
- Gmail or Outlook
Nothing sent. Everything is waiting for you.
What a midday summary looks like (illustrative)
What you get
A day with your email agent
Three sweeps while you work, one learning run while you sleep. You stay in charge of everything that goes out.
Morning sweep
The overnight noise is archived and the first drafts are waiting before your first coffee.
Midday sweep
The morning's new mail sorted: cleared, drafted, or turned into a one-line question for you.
Evening sweep
Last drafts of the day, plus a list of anything still waiting on you.
Learning run
It compares every draft with what you actually sent, turns your edits into rules, and gives you a scorecard for the morning.
Before you start
What you need
Nothing technical. If you can paste text into a chat window, you can build this.
An AI assistant connected to your email
It needs to read your inbox and sent mail, create drafts and run on a schedule. I use Claude with its Gmail connector, and there is one for Microsoft 365 (Outlook) too. Check that your plan includes connectors and scheduled tasks.
Permission, if it's a work account
On a company account, your IT team usually has to switch the email connector on before you can use it. Ask first, and check your company's AI policy.
10 minutes to hear your own voice
The agent plays back how you write. Correcting it is the most valuable 10 minutes of the whole setup.
Pick your version
The two versions
Start with Version 1. Move to Version 2 one type of reply at a time, once the nightly scorecard shows it has earned it.
Version 1 - drafts only
- What the AI does
- Archives the noise, drafts replies in your voice, asks you questions, learns every night
- What you do
- Check the drafts, edit if you need to, and send
- What it sends
- Nothing. Every email still goes out from you
- What it needs
- An AI assistant with an email connector and scheduled tasks
- Risk
- Very low
Version 2 - earned autonomy
- What the AI does
- All of that, and sends the simple replies you have approved, such as confirming a meeting you have already agreed
- What you do
- Approve each type of reply, one at a time, and skim what went out in the summary
- When
- A type of reply qualifies once you have sent its drafts unchanged 10 times in a row. The nightly review tells you
- What it needs
- Permission for your assistant to send email
- Risk
- Low, as long as the approved types stay narrow
How to build it
6 steps
Steps 1 to 5 are the 45-minute setup, and the shortcut prompt can do most of them with you. Step 6 is your daily routine.
Make a home for it 5 minutes
- Create a private project or folder called "Email agent" in your AI assistant. The agent keeps 3 documents there: your Voice profile, your Email playbook and a Draft log. The log holds the text of its drafts, so keep it somewhere only you can see.
- Connect your email, and check the assistant can see your Sent folder as well as your inbox.
Teach it your voice 20 minutes
Paste the voice and playbook prompt. It reads the emails you have sent in the last 90 days, then plays back what you write about, how you write and how your tone shifts with different people.
Correct anything that isn't you, and say what you would like to improve rather than copy. Most people learn something about their own writing here.
Agree the rules 10 minutes
The same prompt then interviews you: what to clear out, who it should never draft for, when to ask you instead of guessing, and the standing facts people keep asking you for. It writes them into your Email playbook.
Schedule the sweeps 5 minutes
Create a scheduled task that runs at 7am, 12.30pm and 5pm on working days (or whenever suits you), and paste in the sweep prompt. Run it once by hand and read the drafts it makes.
Schedule the learning run 5 minutes
Create a second scheduled task for every night at about 11pm, after your last email of the day, and paste in the nightly review prompt.
Every day 10 to 15 minutes
- Open your drafts. Edit freely, then send.
- Answer its questions, in a line each.
- Make your changes in the draft, not in a fresh email: your edits are how it learns.
- Read the morning scorecard. When it recommends approving a type of reply, you decide. To approve, just tell your assistant: "Add meeting confirmations to Approved to send".
What makes it great
The ingredients
All of these are already built into the prompts. You just answer the setup questions.
Start with your voice
90 days of your own sent mail tells the agent more than any description you could write of yourself. Playing it back to you is how you catch what it got wrong.
Your edits are the training data
Every night it compares its drafts with what you sent. The same change made twice becomes a rule. This is what turns a generic assistant into yours.
First, is it already dealt with?
Much of a busy inbox is finished conversations. The agent reads the whole thread and skips it if you replied last, they only said thanks, or a draft already exists.
Draft is not send
Nothing leaves your inbox until you send it, or until a type of reply has earned its place on your approved list with 10 unchanged sends in a row.
Know when to stay out
Deals, hiring, money, legal, people issues and anything only you know: the agent asks you a one-line question instead of guessing.
Never promise what it can look up
Your standing facts live in the playbook, so drafts include the address, the link or the bio instead of "I'll send it shortly".
Archive, never delete
Anything it clears can be found again in seconds. Nothing permanent happens without you.
The shortcut - optional
Let your AI build it with you
If your AI assistant can open web pages, paste this in. It reads this guide, learns your voice, agrees the rules with you and sets up the scheduled tasks, so you can skip most of steps 2 to 5. If it can't open web pages, use the 3 prompts below instead.
I'd like to build an email agent that writes like me and learns from my edits, following this guide: https://www.digitalpeople.online/agent-builder/email Please open and read the whole page first, including the three prompts on it. Then: 1. Check that you can read my sent mail, create drafts in my inbox and run scheduled tasks. If anything is missing, tell me exactly how to switch it on. 2. Run the voice and playbook prompt with me now: learn my voice from my sent mail, play it back to me, then agree the rules. 3. Set up the sweep prompt to run three times a day and the nightly review prompt to run every night, filled in with my details. 4. Run one sweep now, drafts only, so I can see the result. If you can't open web pages, tell me, and I'll paste the three prompts from the page instead.
Prompt 1 of 3 - use once
The voice and playbook prompt
Paste this into your AI assistant. It learns how you write from your sent mail, plays it back to you, then agrees the rules and writes your playbook.
You are going to help me set up an email agent that looks after my inbox in my voice. Today has two parts: learn how I write, then agree the rules with me. Do not send, archive or delete anything today. PART 1 - LEARN MY VOICE 1. Read the emails I have sent in the last 90 days (my Sent folder). Use only text I wrote: skip quoted replies, forwarded text, signatures, calendar invites and automatic messages. If there are more than about 300, take a spread across the whole 90 days rather than just the most recent. 2. Work out, from the evidence: - What I write about: the main topics, the kinds of people I write to, and the kinds of email I send again and again (for example scheduling, introductions, declines, updates, thank-yous). - How I write: typical length, greetings and sign-offs, sentence length, how direct I am, words and phrases I use a lot, punctuation habits, and how I use lists, links and emoji. - How my tone changes with the audience: colleagues, clients, senior people, friends and family, people I don't know. - What I never do: words I never use and habits I avoid (for example long preambles, exclamation marks, "Kind regards"). 3. Play it back to me as a short voice profile: 8 to 12 bullet points, each with a short example quoted from my own emails, with names, numbers and anything private trimmed out. Then ask me three things: what is wrong, what is missing, and whether there is anything about how I write now that I would like to improve rather than copy. Update the profile with my answers. PART 2 - AGREE THE RULES Interview me in short rounds of 3 to 5 questions. Offer examples so I can answer quickly, and skip anything I say I don't want to answer. - Clear out: which senders and kinds of email you can archive without asking (newsletters I never read, notifications, receipts, cold sales), and which I always want to see. - Never draft: people and topics I always handle myself (for example my boss, my family, pay, HR, legal, or anything about a deal or a hire). - Always ask me: situations where you should ask me a short question rather than guess. - My standing facts: the details people regularly ask me for (job title, company details, office address, my booking link, a short bio, useful links), so drafts include them instead of promising to send them later. - Timing: when the sweeps should run (suggest 7am, 12.30pm and 5pm) and where I want the summaries (an email to myself or a chat message). - One day, sending: are there simple kinds of reply I might later be happy for you to send without me (for example confirming a meeting time I have already agreed)? List them, but do not switch any on. Then write three documents and save them where my scheduled tasks can read them: 1. "Voice profile" - the profile we agreed. 2. "Email playbook" - the rules above, my standing facts, a section called "Approved to send" that says "None yet", and a section called "Lessons learned", empty for now, which the nightly review will add to. 3. "Draft log" - empty for now. Each sweep records its drafts here. Finish by telling me in two lines what to do next: schedule the sweep prompt, and schedule the nightly review prompt.
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Prompt 2 of 3 - runs 3 times a day
The sweep prompt
Paste this into a scheduled task that runs at 7am, 12.30pm and 5pm, or whenever suits you. Fill in the bits in [square brackets]: how many drafts per sweep (5 is a good start), and whether you want the summary by email or as a chat message.
Go through my inbox now and do an email sweep, following my Email playbook and Voice profile exactly. I am not watching this run, so do not ask me questions here: put them in the summary.
1. READ FIRST
- The Email playbook (rules, standing facts, "Approved to send" and "Lessons learned") and the Voice profile.
- The Draft log, so you know what you have already drafted.
2. WHAT TO LOOK AT
Everything that has arrived since the last sweep (the time is noted at the top of the Draft log; if there is none, the last 12 hours), plus any thread I have starred or flagged as needing a reply.
3. FOR EACH THREAD, FIRST: IS IT ALREADY DEALT WITH?
Read the whole thread, not just the latest message. Skip it if:
- the last message is from me;
- their last message only closes the conversation ("thanks", "speak soon", an out-of-office);
- it already has a draft, mine or yours.
Judge by the latest messages, never by the subject line.
4. SORT EACH THREAD INTO ONE OF FOUR
- CLEAR: it matches the playbook's clear-out list. Archive it. Never delete anything.
- DRAFT: a reply you can write well from the thread and the playbook: scheduling, thank-yous, introductions, simple questions, routine requests, polite declines.
- ASK ME: it needs my judgement or facts only I have (money, deals, hiring, people issues, legal, anything on my never-draft list). Do not draft. Write me one short question instead.
- LEAVE: nothing is needed from me (for your information, or I am only copied in). Leave it in the inbox.
5. DRAFT CAREFULLY
- At most [5] drafts per sweep, most important first. List the rest in the summary.
- Re-open the thread just before you write, in case something new has arrived.
- Reply to whoever sent the latest message, and keep everyone else who was on it unless that is clearly wrong. Never put me on my own draft.
- Write in my voice: follow the Voice profile and every rule in "Lessons learned".
- Use my standing facts. Never promise to send something later that you could include now.
- If the angle is not obvious (a pitch, a sensitive reply, a first approach), still draft it, but flag it with "Check the angle" in the summary.
- Save each reply as a draft in its thread. Do not send anything, unless the reply is in a category on my "Approved to send" list and the thread is routine. If in doubt, draft.
- Add one entry per draft to the Draft log: date and time, subject, who it is to, the category, and the full text of the draft.
6. SUMMARY
Send me one short summary [by email to myself / as a chat message]:
- Anything you sent, quoted in full. Normally this is "Nothing sent".
- Questions for me, one line each, naming the thread.
- Drafts waiting for me, one line each, with any "Check the angle" flags.
- What you archived, as counts by type, plus anything you were unsure about.
Finally, note the time of this sweep at the top of the Draft log. If there was nothing to do, say so in one line.
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Prompt 3 of 3 - runs every night
The nightly review prompt
Paste this into a scheduled task that runs every night at about 11pm, after your last email of the day. Fill in the bits in [square brackets].
Run tonight's learning review for my email agent. I am not watching, so do not ask me questions: make the sensible call and say what you decided in the report. 1. COMPARE For every draft in the Draft log from the last 24 hours, plus any older ones not yet reviewed, find out what actually happened: - SENT AS IS: I sent your draft with no meaningful change. - EDITED: I sent it with changes. Compare your draft with what I sent, line by line. - REWRITTEN: I sent something substantially different. - BINNED: I deleted the draft, replied in a different way, or did not reply. Also read the emails I sent today that you did not draft. They show my voice too. 2. LEARN Look for patterns in my changes, especially the same change made more than once: words I cut or swapped, length, greetings and sign-offs, how direct I was, what I added (a fact, a link, a warmer line) and what I took out (a hedge, a sales line, an over-apology), and any kinds of email where I bin your drafts. A one-off correction to the facts of a single email is not a lesson. 3. UPDATE THE PLAYBOOK - Add each new lesson to "Lessons learned" in the Email playbook as one plain rule with a short before-and-after example, with names and private details trimmed out. If it overlaps an existing rule, improve that rule rather than adding a new one. Keep the section short: past about 30 rules, merge the similar ones. - If a lesson is about how I write in general, update the Voice profile too. - Never change my never-draft list or my "Approved to send" list yourself. - If one category of draft has now been sent as is at least 10 times in a row, recommend adding it to "Approved to send" in your report. Only I can approve it, by telling you to add it. - Mark each reviewed draft in the Draft log as reviewed, with what happened to it. 4. REPORT Send me a short note [by email to myself / as a chat message] to read in the morning: - Scorecard: sent as is, edited, rewritten and binned, for today and for the last 7 days. - What you learned, one line each, with the rule you added or changed. - Any category ready to be approved to send, with the evidence. - Anything that went wrong. If there were no drafts to review, say so in one line.
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Built by Ben Legg (Digital People), from the email agent I use every day. If you build one, I'd love to hear how it gets on.
The series
More agents worth building
This is one of a series of free guides to small, useful agents: the playbook written once, the agent doing the daily work, a human in the loop. It's the same pattern we use to build agents at Digital People. One page per agent, each with the prompts you need.
- No. 1 - An email agent that writes like youYou are here
- No. 2 - A daily news show for your childrenRead it
- No. 3 - Calendar managementComing soon
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Insights and advisory services from battlefield-tested operator and ex-COO of Google Europe, Ben Legg.
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