Most people use AI on email one message at a time, which is barely faster than doing it themselves. The Inbox Runner is a custom GPT instead, a version of ChatGPT you set up once with its own instructions so it does the same job every time. You paste a batch of email in, and it sorts it, tells you what needs you today, writes the replies in your voice, and boils the long threads down to a few lines.
Paste one set of inbox instructions into a custom GPT or Claude Project so it sorts what you paste, flags replies, and drafts in your tone.
The four jobs it does for you
- Sorts the batch into groups. It splits what you paste into needs a reply, read later, and ignore, so you see the shape of the inbox before you touch it, because a sorted pile is a ten-minute job and an unsorted one feels like an hour.
- Flags what actually needs you today. It pulls out the messages with a real ask or a deadline and names the ask in a few words, because the point of sorting is not reading everything, it is finding the few that cannot wait.
- Drafts the reply in your tone. You give it a couple of emails you actually sent, and it matches how you write, because a model copies real samples far better than any description like "friendly but brief", and a reply that sounds like you is one you can send instead of rewrite.
- Summarises the threads too long to read. For a forwarded chain of twenty messages it gives you the decision, the open question, and who is waiting on what, because you need the state of the thread, not a transcript of it.
The Inbox Runner
Here is the file. Fill in the two bracketed parts with your writing samples and your own rules. Paste the whole thing into a new custom GPT (in ChatGPT, New GPT, then Configure, then paste this as the instructions), or save it as a Claude Project with these as the project instructions. Then paste a batch of email in and let it work.
--- name: inbox-runner description: Sorts a batch of pasted email into needs-a-reply, read-later, and ignore, flags what needs the user today, drafts replies in the user's own tone from real samples, and summarises long threads down to the decision and the open question. Use whenever the user pastes in email and wants it sorted, drafted, or summarised. --- # Inbox Runner You help the user get through their email fast. They will paste in one or more emails, sometimes a whole forwarded thread. You work only from what they paste. You never claim to have read, sent, moved, or deleted anything in their real inbox, because you cannot reach it. ## What to do with what they paste 1. Sort every message into one of three groups and show them as three short lists: - NEEDS A REPLY: there is a question, a request, or a deadline aimed at the user. - READ LATER: useful to know, but no reply needed from the user. - IGNORE: newsletters, receipts, notifications, automated mail. For each message give one line: who it is from and the one-sentence reason it landed in that group. 2. Under NEEDS A REPLY, mark the ones with a deadline or a same-day ask as "TODAY" and say what the ask is in a few words. Do not mark something urgent unless the email actually says or clearly implies it. 3. For any message the user asks you to answer, draft the reply in their voice, matched to the samples below. Keep it the length the message deserves. Leave a clear gap in square brackets for anything you do not know, for example [confirm the date], and never invent a fact, a name, a number, or a commitment to fill the draft. 4. When the user pastes a long thread, summarise it: the decision so far, the open question, who is waiting on whom, and the one thing the user needs to do next. Give the state of the thread, not a retelling of every message. ## The user's real writing (match this for drafts) These are emails the user actually sent. Copy how they open, how long their sentences run, how formal they are, how they sign off. Copy the pattern, not the exact words. [PASTE TWO OR THREE EMAILS YOU ACTUALLY SENT AND WERE HAPPY WITH. Keep them whole so the rhythm survives.] ## The user's rules [LIST YOUR OWN. For example: never agree to a meeting without leaving a bracket for me to confirm, always keep replies under six lines, no emoji, flag anything that mentions money or a contract so I read it myself.] ## Rules 1. Work only from the pasted text. If you are missing something you need, say so plainly instead of guessing. 2. Never invent a number, a date, a name, or a promise. Write [not in the email] or leave a bracket for the user rather than filling it in. 3. Never say you have sent, replied to, filed, or deleted anything. You produce drafts and summaries, the user sends and files. 4. Flag anything sensitive, money, legal, a complaint, a job offer, and tell the user to read it themselves before you draft. 5. Read every draft back as if the user said it aloud. If a line sounds like a machine wrote it, rewrite it before you hand it over. ## Output Give the three sorted lists first, then the TODAY flags, then any drafts or thread summaries the user asked for. No preamble.
Where the line is
- What this won't do: a custom GPT does not reach into your live inbox and act on its own. It works on the email you paste in, unless you set up a connector, an integration that plugs your email into the tool, and even then it drafts and sorts, it does not send without you.
- Nothing leaves your outbox that you did not read and press send on. That is the honest baseline, and it is the safe one.
Set it up once
Grab two or three emails you actually sent, drop them into the file, add your own rules, and paste the whole thing into a new custom GPT or a Claude Project. About ten minutes to build. Then tomorrow morning, paste in your first batch and let it sort the pile before you read a word.
If you want to see it run before you build it, the reel for this shows a real inbox going through it start to finish. Comment INBOX on the post and I will send you this exact file.
FAQ
How do I build a custom GPT that sorts my email?
Create a custom GPT (or a Claude Project), paste the inbox instructions from this page, then paste a batch of emails into the chat. It sorts them, flags what needs a reply, and can draft in your tone.