How to build a Claude inbox assistant for Gmail that sorts email every hour

I run multiple businesses, for me and for my clients, and I have multiple email accounts. For a long time email was the part of my day I dreaded most.

It got to the point where I just didn't read my emails anymore. I'd open an inbox, see a wall of newsletters, receipts, membership renewals and tool notifications, and close it again. Somewhere in that pile was an email from a real person who needed an answer from me, and I constantly missed it.

So I built an inbox assistant. Every hour it goes through my inboxes, files everything that isn't from a person into the right folder, finds the people who are waiting on me, writes the reply, and puts a task in ClickUp so the reply actually gets sent.

Now when I open my inbox, what's there is the people I need to reply to, and the replies are already written.

What you're building

This is the Gmail version, because it's the easiest one to start with. Every hour, your inbox assistant will:

Sort. Everything that isn't from a person goes into a label: newsletters, receipts, subscriptions and tool notifications, calendar invites, and cold sales pitches. It remembers every sender, so next time that sender goes straight to the same place. Nothing is deleted.
File the old mail. Anything over 30 days old that you haven't starred and aren't replying to goes into the label that sender's mail already lives in. Claude suggests the labels first and you say yes once. If it can't find a home for an email, it leaves it where it is and tells you.
Find the people waiting on you. It looks at emails from real people in the last seven days and checks your Sent folder. If you've already replied, it leaves that email alone. Auto-replies, calendar invites, "no-reply" senders and review requests don't count.
Draft. It reads the whole conversation, including what you've already said, and answers the question that's still open, not just the last line. It saves the reply as a draft inside that conversation in Gmail and stars the email. Anything it can't know, like a date, a price or a yes, goes in square brackets for you to fill in. It never sends anything.
Set up the task. It creates a task in ClickUp called "Reply to [name] - [subject]", due that day, with the draft, their email and a link to the conversation in the description.

If it's a sales pitch from someone you've never emailed, it doesn't star it or draft anything. It files it in Cold Outreach and remembers the sender, so that one doesn't come back.

So your day looks like this. You open ClickUp, you see "Reply to Jo - invoice question", and the draft is right there in the task. You click through to Gmail, tweak it and press send.

Mine runs across all of my email accounts, and most of them aren't Gmail, so a small script does my filing and Claude writes the replies. You don't need that for a Gmail account. Claude can do the whole job through the Gmail connector.

Get the skill

I've written the whole job up as a skill you can download, with nothing of mine in it.

Download the Inbox Assistant skill →

A skill is a set of instructions Claude reaches for on its own, so you never have to explain the job again. If you want to know how they work, I explain it in How to Build a Claude Skill.

Inside the download is the skill itself and a setup guide with every prompt from this post in the same order. The skill doesn't know anything about you yet. Claude fills that in with you in Step 3, and keeps it in a rules file in your AI brain folder.

How this works

There are four parts, and you set them up in this order.

The skill is the job: how to sort, who counts as waiting, how to draft, what goes in the task.
The task manager is where the reply tasks land.
Gmail is the inbox it works on.
The routine is what makes it run every hour without you opening a chat. A skill is an employee who knows the job. A routine is what makes them turn up.

What you need before you start

The Claude desktop app, with the Claude Code tab.
A Gmail account. If you have more than one, start with the busiest.
ClickUp, or whichever task manager you already use. The steps say ClickUp; swap in yours.
Your AI brain, if you want the drafts to know your business. Claude can't answer a question about your business if it has never been told anything about it. If you haven't set that up, do it first: The Co-Founder Setup.
The Inbox Assistant skill from the download above.

You don't need a developer, Zapier or any code.

One thing to know about Gmail before you start: Gmail calls folders "labels". When this post says an email moves to a folder, it means Claude adds the label and archives the email, which takes it out of your inbox. Archived email is still in Gmail under that label and under All Mail. Nothing disappears.

Step 1 - Install the skill

Unzip the download. Inside you'll find a folder called inbox-assistant with a file called SKILL.md in it.

Open the Claude desktop app.
Go to Customise.
Then Skills.
Then Add Skill.
Upload the SKILL.md file from the inbox-assistant folder.

It's now available in every chat.

What you'll see: Inbox Assistant in your list of skills.

Step 2 - Connect your task manager

This is where the "Reply to" tasks will go.

Open Settings in the Claude app, then Connectors.
Find ClickUp and click Connect.
Sign in on ClickUp's own screen and allow access.

You sign in on ClickUp's screen, not in a chat. Your password never goes in a message, and that's a rule worth keeping for everything you build.

Step 3 - Connect Gmail and set it up with Claude

Now open a chat. Click the Claude Code tab and start a new chat. If you have a folder for your AI brain, attach it with the + button.

I've just installed the inbox-assistant skill & connected you to ClickUp.
Check you can see both. Now I need to connect you to my Gmail. Tell me
exactly where to click. I'll sign in on Google's screen myself - I'm not
putting any passwords in this chat.

Because it's Gmail, this is the easy one. There's a connector for it, the same as ClickUp. Claude will send you to click something like this.

Open Settings, then Connectors.
Find Gmail and click Connect.
Sign in with Google and allow access.

What you'll see: Claude lists your Gmail labels and your ClickUp spaces back to you, which is how you know it can reach both.

Then, in the same chat:

Now set up my inbox-assistant skill with me. Ask me one question at a
time. Create inbox-rules.md in my AI brain folder & write my answers into
its Setup section. Don't move any email yet.

Claude asks for your email address, the ClickUp list the reply tasks should go in, and the status and timezone to use. A routine starts every run with no memory of the last one, so everything it knows about you has to live in a file it reads each time. That's what inbox-rules.md is.

What you'll see: a new file in your AI brain folder you can open and read. This is the file you'll add to as it learns, so it's worth knowing where it is.

Step 4 - Decide the labels

Before anything moves, let Claude look at what's actually in there.

Look at the last 200 emails in my inbox. Group them by what they are -
newsletters, purchases & receipts, subscriptions & tool notifications,
calendar invites, cold sales pitches, & emails from real people. Show me
each group with a count & three example senders, then suggest the labels
I need. Include labels for my older mail, using the labels I already
have first. Don't move anything yet.

What you'll see: a short table with a count for each group and the labels Claude suggests.

Change anything you want ("put Canva and Stripe under Subscriptions & Tools, not Receipts"), then:

Create those labels in my Gmail & write which senders go to which label
in inbox-rules.md.

Check the left-hand sidebar in Gmail. The new labels will be there, empty for now.

Step 5 - Teach it how you write

The drafts are only useful if they sound like you.

Read the last 30 emails I've sent that were written to a person, not
automated. Write down how I write: how I open, how long my emails are,
how I sign off, the words I use & the ones I never use. Add it to the
Voice section of inbox-rules.md.

Mine says I open with "Hi" and a first name, never "Dear". I use short lines, say the thing and stop. I sign off with "Thank you" or "Kind regards" and my name on its own line.

What you'll see: a Voice section in the rules file. Read it. If something's wrong, tell Claude and it will fix it.

Step 6 - Do one run while you watch

Use my inbox-assistant skill to do one run now, but stop before you
create any ClickUp tasks. Tell me how many emails you filed, how many
stayed, which ones you starred & which drafts you saved.

What you'll see: a short report, stars on the emails that need you, and drafts sitting inside the right conversations in Gmail.

Open Gmail and look at what's left in your inbox. If something is still there that shouldn't be, tell Claude "anything from this sender goes to Newsletters from now on" and it goes into the rules file.

Then open one of the drafts. Anything Claude couldn't know is in square brackets, like "[confirm the date]". That's on purpose. A draft that guesses at a price or a date is worse than no draft, because you might send it. It also won't agree to money, a contract or a decision for you. It writes the reply and leaves the decision in brackets.

Step 7 - Set up the routine

Up to now the assistant only runs when you ask it to in a chat. The routine is what makes it run every hour on its own. You set it up by telling Claude, in the same chat or a new one.

Set up a routine that runs every hour from 7am to 9pm & uses my
inbox-assistant skill. My rules file is inbox-rules.md in my AI brain
folder. Create the reply tasks in ClickUp, in the list in my rules file.
Keep the routine short, because the skill holds the job. Finish every
run with the report from the skill.

Claude writes the routine, saves it, and tells you when it'll first run. If you want to pause it or change the hours later, ask Claude in any chat.

The routine is short on purpose. It only says when to run and which skill to use. Everything about how to do the job stays in the skill, so when you improve the skill, the routine picks it up on the next run.

The skill also keeps a log of every email it has dealt with, and checks it before it creates a task. Without that log, the same email would get a new task every hour.

What you'll see: at the next hour, it runs on its own. Check the report, your inbox and your ClickUp list after the first couple of runs.

If you want to know more about how routines work, I explain it in How to Build a Claude Routine.

The catch, and the fix

For the first week it will leave things in your inbox that shouldn't be there. That's the rule doing its job. When it isn't sure, it leaves the email with you rather than filing something important into a label you never open. Each time you see one, tell Claude which label that sender belongs in and it goes into the rules file. The inbox gets cleaner every day because the rules file gets longer.

The drafts will need tweaking at first. Every time you change a draft before you send it, tell Claude what you changed and ask it to add that to the Voice section. The drafts get closer to yours every week.

It only runs while your Mac is awake with Claude open. If the laptop is shut on the hour, it runs when you next open it. For most people that's fine, because email arrives while you're working anyway. If you want it running when you're not there, I explain the options (a spare Mac that never sleeps, or the cloud) in How to Build a Claude Routine.

What this looks like as a business

Every client you work with has an inbox that looks like mine did. Setting this up for them is a systems job, and you're paid for knowing what to build. Build one for yourself first, then it's something you can offer.

Start with one

Start with one inbox. Install the skill, connect ClickUp and Gmail, and do Steps 3 to 6 while you watch for a few days, fixing the rules as you go. When you trust what it's filing and the drafts sound like you, set up the routine.

If you haven't got your AI brain set up, that's the foundation for all of this: start here.

How I use Claude to sort my inbox every hour (and draft the replies)