# Build a Custom GPT That Writes Sales Follow-Up Emails

> Build a Custom GPT that writes short, specific sales follow-up emails from your own playbook and pricing. Free, step-by-step ChatGPT lesson for sales reps.

Source: https://learn.ynteractive.com/content/custom-gpt-sales-follow-up-email-writer · Updated 2026-11-03 · Free from Stepthrough (https://learn.ynteractive.com)

## Practice it step by step

[Start the free practice](https://learn.ynteractive.com/modules/chatgpt-custom-gpt-sales)

[Take the free module: why it matters, practice and a quick check →](https://learn.ynteractive.com/courses/ai-for-sales/14)

You do every step yourself in a practice copy of ChatGPT. It checks your work as you go, and “Do it for me” finishes any step you get stuck on. Free, about 8 minutes, and nothing touches your real accounts. [Open full screen](https://learn.ynteractive.com/modules/chatgpt-custom-gpt-sales)

Free · Live now · [AI Automation for Sales](https://learn.ynteractive.com/content/industry/sales) · [ChatGPT](https://learn.ynteractive.com/courses/chatgpt-for-everyday-work) · Google Drive · ~8 min · 16 steps · Beginner

Updated November 3, 2026. Built against the tool’s current screens and checked step by step. [How we check this lesson](https://learn.ynteractive.com/content/about#how-we-check)

**OpenAI is retiring custom GPTs on December 11, 2026 and replacing them with plugins.** [Here’s how to save yours →](https://learn.ynteractive.com/content/explainers/chatgpt-course-for-work#save-your-custom-gpt-before-december-11)December 11, 2026 is the scheduled retirement date in OpenAI’s custom GPT retirement FAQ for Enterprise workspaces; OpenAI says other plans may follow the same timeline. Checked October 17, 2026. See [OpenAI’s migration guide](https://learn.chatgpt.com/docs/migrate-custom-gpts).

**Custom GPTs are being retired;** see [ChatGPT Projects vs Gemini Gems vs Gemini Notebook: Which to Use](https://learn.ynteractive.com/content/chatgpt-projects-vs-gemini-gems-vs-notebooklm). This lesson stays here for reference, but it is no longer in our lesson lists.

Ask plain [ChatGPT](https://learn.ynteractive.com/courses/chatgpt-for-everyday-work) for a [follow-up email](https://learn.ynteractive.com/content/glossary/follow-up-email) after a demo and you get emojis, all caps and a limited time offer nobody approved. In this free lesson you build a sales follow-up writer for Northwind Scheduling Software: a [Custom GPT](https://learn.ynteractive.com/content/glossary/custom-gpt) that knows the product, the plans and your team's rules, and writes a short email a prospect might actually answer.

**Heads up:** OpenAI is retiring Custom GPTs and moving them to plugins (December 11, 2026 for Enterprise workspaces; other plans may follow), and creating new GPTs is ending. This lesson still teaches the core skill (a role, clear rules and a reference document), and a ChatGPT Project is where to use it today.

## At a glance

| Question | Answer |
| --- | --- |
| What you build | See why generic prompts give generic results, then build a Custom GPT that knows your product, pricing and rules and writes short, useful follow-up emails in your voice. |
| Tools | ChatGPT |
| Time | About 8 minutes, 16 steps in 6 parts |
| Level | Beginner, no coding needed |
| Cost | Free |
| Ways to learn it | [Practice it step by step](https://learn.ynteractive.com/modules/chatgpt-custom-gpt-sales) |

### The 6 parts, in short

1. Ask ChatGPT: Click the message box, Type a prompt, Send the message.
2. Explore GPTs: Open the More menu, Open GPTs, Create a GPT.
3. Name your GPT: Click the Name field, Name your GPT.
4. Add instructions: Click the Instructions field, Paste your instructions.
5. Upload knowledge: Upload your sales playbook, Open the sales playbook, Attach the document.
6. Test your GPT: Start chatting, Type the same prompt, Send the message.

**Start here first:** [Get On-Brand Social Posts Every Time using a ChatGPT Custom GPT](https://learn.ynteractive.com/content/custom-gpt-social-media-assistant). This Sales version follows the same build with its own example business.

## What you will build: a sales follow-up email writer

You start by giving ordinary ChatGPT one bare [prompt](https://learn.ynteractive.com/content/glossary/prompt): write a follow-up email to a prospect after our sales demo. The reply is the email every buyer deletes. The subject line shouts about an amazing opportunity. The body promises to revolutionize the business, talks about crushing the competition, and ends with a limited time offer and 'just checking in'. There is nothing from the demo in it.

Then you build a Custom GPT called Sales Follow-Up Writer. You give it written rules and a sales playbook, and you send the exact same prompt again. This time you get a plain subject line, one line of thanks, three short bullets on the features that fit the prospect, the Team plan price at $39 per user per month because the prospect asked, and one next step: a 14-day free trial set up on a 20-minute call, with two specific times to choose from.

## Who this is for

This lesson is for sales reps, account executives, SDRs and sales managers who write the same kinds of follow-ups every day. After a demo, after a trial, after a prospect goes quiet. You do not need any AI experience or technical background. If you can copy and paste, you can build this.

## What goes into the rules and the sales playbook

The instructions read like a brief for a new rep. Sound like someone who listened on the call, not a pushy salesperson. No emojis, no all caps, and none of the pressure phrases: act now, limited time, don't miss out, last chance. Every email gets a subject under 8 words, one line of thanks, a 2 to 3 bullet recap of the features that match the prospect's need, a price only if they asked, and exactly one next step with a clear ask. Under 150 words.

The content rules keep the email honest. Only mention features and prices from the playbook, and never invent a discount. If a detail is missing, like the prospect's first name, the GPT leaves a [bracket] for the rep to fill in instead of guessing. It never promises results like 'double your bookings' and never talks down other products.

The playbook PDF holds the facts: who Northwind sells to (service businesses with 2 to 50 staff), the features (online booking, reminders, a shared calendar, recurring jobs, simple reports), the three plans at $19, $39 and $59 per user per month, the 14-day free trial, the follow-up rules, and a sample email.

## Why it works

Plain ChatGPT has never seen your product or your price list, so it fills the gap with the loudest sales copy it knows. A Custom GPT carries your rules and your playbook into every chat, so you stop re-explaining the product each time. The rules also stop the mistakes that cost deals, like a price that is not on the sheet or a promise the product cannot keep.

## Common follow-up mistakes this avoids

- The empty check-in. 'Just circling back' gives the prospect nothing to answer. Every email here recaps what they said and asks for one thing.
- Pressure. Fake deadlines and all caps make a small business owner stop replying. The rules ban them.
- Made-up numbers. The GPT quotes only the plans in the playbook, so no rep promises a price finance never approved.
- Too long. A 150-word limit keeps the email readable on a phone between jobs.

## How to use this on your sales team

Swap in your own playbook, price sheet and two or three follow-ups that got replies. Then paste your call notes, the prospect's name and what they cared about, and let the GPT draft the email while you check the details. Share the same rules and playbook with the team, in a shared ChatGPT Project now that Custom GPTs are being retired, so every rep starts from the same rules and the same prices. It works for post-demo recaps, trial check-ins and re-engaging deals that went quiet. You still read every email before you send it.

## Try it yourself, free

Reading the steps is a start. Doing them is how it sticks. The interactive module walks you through every click in a practice copy of ChatGPT, checks each step, and never touches your real accounts.

[Start “Build a Custom GPT That Writes Sales Follow-Up Emails”](https://learn.ynteractive.com/modules/chatgpt-custom-gpt-sales)

## Step by step: Build a Custom GPT That Writes Sales Follow-Up Emails

All 16 steps of the interactive module, in order. In the module you watch each one, then do it yourself in a practice copy that checks your work.

### 1. Ask ChatGPT

1. **Click the message box.** Click the **message box** at the bottom to start typing.
   Most people open ChatGPT and just start chatting. They type a quick prompt, get a generic answer, and wonder why AI feels underwhelming. Let's see exactly what that looks like.
2. **Type a prompt.** Click the **Paste prompt** button on the message box (or type anything close to it): **Write a follow-up email to a prospect after our sales demo**
   We will ask ChatGPT to write a follow-up email after a sales demo. No context, no instructions, just a bare prompt — the way most people use it.
3. **Send the message.** Click **Send**.

### 2. Explore GPTs

4. **Open the More menu.** Read the response — it is generic and full of emojis. Now click **More** in the sidebar.
   Look at that. Emojis, all caps, a limited time offer you never made, and not one detail from the demo. No prospect would reply to that. That is what happens when you give AI zero context. Let's fix that.
5. **Open GPTs.** Click **GPTs** to explore Custom GPTs. In the current ChatGPT the sidebar says **Explore** and there is no More menu, so you can also go straight to chatgpt.com/gpts.
   A Custom GPT is your own version of ChatGPT with built-in instructions and knowledge. Instead of explaining who you are every time you chat, the GPT already knows. In the current ChatGPT that button is called Explore, or you can go straight to chatgpt dot com slash gpts.
6. **Create a GPT.** Click **+ Create** to start building your Custom GPT.
   This is the GPT store. You can browse what others have built, but we are going to create our own.

### 3. Name your GPT

7. **Click the Name field.** In the real builder you start on the **Create** tab, which is a chat. Click the **Configure** tab first, then click the **Name** field.
   This is the GPT builder. On the left you configure it, on the right you can preview it. First, give it a name. In the real builder you start on the Create tab, which is a chat, so click the Configure tab first.
8. **Name your GPT.** Enter the name: “Sales Follow-Up Writer”
   Call it Sales Follow-Up Writer. This is what shows up when you open it later.

### 4. Add instructions

9. **Click the Instructions field.** Click the **Instructions** field.
   Now here is the important part. The instructions tell the GPT exactly how to write, what tone to use, what never to promise, and how to lay out every email.
10. **Paste your instructions.** Paste in the instructions to add your follow-up rules.
    These instructions cover the tone, the email layout, the pricing rules, and what the company actually sells. This is what turns a generic chatbot into a tool that writes like your best rep.
    ```text
    You are the follow-up email writer for the sales team at Northwind Scheduling Software. We sell online scheduling software to small service businesses: cleaning companies, salons, lawn care crews and repair shops. You write follow-up emails that a sales rep sends after a call or a demo.
    
    VOICE & TONE
    - Sound like a helpful rep who listened on the call — never like a pushy salesperson.
    - Be direct and specific. Mention what the prospect told us and the features that fix it.
    - Use short sentences. Write at a 7th-grade reading level.
    - Never use emojis. Never use all caps for emphasis.
    - Never use pressure words: act now, limited time, don't miss out, last chance, or game-changer.
    
    STRUCTURE
    - Subject line: plain and specific, under 8 words.
    - Open with one line of thanks. No small talk.
    - Recap in 2-3 short bullets: the features that match what they need.
    - Give the price only if they asked about it, using the Sales Playbook.
    - End with exactly one next step and a clear ask, like a time for a short call.
    - Keep every email under 150 words.
    
    CONTENT RULES
    - Only mention features and prices from the Sales Playbook. Never invent a price or a discount.
    - If a detail is missing (first name, team size, what they said), use a [bracket] so the rep can fill it in.
    - Never promise results like "double your bookings." Describe what the software does.
    - Never badmouth other products. Focus on what fits this prospect.
    
    COMPANY CONTEXT
    - Northwind has 22 people and has sold scheduling software for 6 years.
    - Every plan starts with a 14-day free trial. No setup fee. Cancel anytime.
    ```

### 5. Upload knowledge

11. **Upload your sales playbook.** Click **Upload files** to find your sales playbook.
    Instructions set the rules. You can also upload files — your sales playbook, your price list, emails that got replies. The GPT uses them as reference.
12. **Open the sales playbook.** Click **Northwind-Sales-Playbook.pdf** to preview it.
    Here is your Google Drive. Find the sales playbook and click it to see what is inside.
13. **Attach the document.** Scroll through the document, then click **Select** to attach it.
    This is your sales playbook: who you sell to, the features, the three plans, the follow-up rules, and a sample email. The GPT will only use these prices.

### 6. Test your GPT

14. **Start chatting.** Click the **message box** in the preview panel to test your GPT.
    Everything is set. We have a name, detailed instructions, and our sales playbook uploaded. Now let's test it with the exact same prompt we used before.
15. **Type the same prompt.** Enter the same prompt: “Write a follow-up email to a prospect after our sales demo”
    Same exact prompt. Word for word. The only difference is that this GPT has our instructions and sales playbook.
16. **Send the message.** Click **Send**.
    Send it and watch the difference.

## Frequently asked questions

**How does the interactive lesson work?**

Each step is shown to you first on the left (Watch). Then you do it yourself in a practice copy on the right (Your turn), and every click is checked. If you get stuck, press Do it for me. It is a practice copy, so no real accounts are touched.

**Is this lesson free?**

Yes. Stepthrough is completely free. To build it for real you need your own ChatGPT account. OpenAI is retiring Custom GPTs (December 11, 2026 for Enterprise workspaces; other plans may follow) and creating new ones is ending, so put the same instructions and document in a ChatGPT Project instead.

**Will the Custom GPT make up prices or discounts?**

The instructions tell it to use only the prices in your playbook and never invent a price or a discount. You should still check every email before it goes out.

**What if I do not have the prospect's details?**

The rules tell the GPT to leave a [bracket] for anything missing, like a first name or team size, so you can fill it in rather than send a guess.

**Can my whole sales team use the same GPT?**

Yes, but not as a Custom GPT for long: OpenAI is retiring Custom GPTs (December 11, 2026 for Enterprise workspaces; other plans may follow). Put the same rules and playbook in a shared ChatGPT Project so every rep writes from them. Check your ChatGPT plan's sharing options.

[Start this module free](https://learn.ynteractive.com/modules/chatgpt-custom-gpt-sales)

- Next in AI Automation for Sales: [Build an n8n AI Agent That Writes Deal Follow-Ups](https://learn.ynteractive.com/content/n8n-ai-agent-sales-deal-follow-ups)

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- [Build an AI Demo Request Form That Qualifies Leads](https://learn.ynteractive.com/content/ai-demo-request-form-lead-qualification): Build a "Book a demo" form in Lovable for Northwind Scheduling Software and connect it to n8n — the AI agent rates each lead hot, warm or nurture, saves it to Google…
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[All 19 modules in AI Automation for Sales](https://learn.ynteractive.com/content/industry/sales)

## More ChatGPT tutorials

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- [Send a Same-Day Follow-up After Every Discovery Call using ChatGPT](https://learn.ynteractive.com/content/chatgpt-discovery-call-follow-up-email-sales): Turn a discovery call transcript into the decisions, the next steps with owners and dates, deal notes for your CRM, and a follow-up email the prospect gets the same…
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## From the blog


[All blog posts](https://learn.ynteractive.com/content/blog)

## Terms in this lesson

Plain-English definitions, each with an example from a free lesson.

[Custom GPT](https://learn.ynteractive.com/content/glossary/custom-gpt) · [Follow-up email](https://learn.ynteractive.com/content/glossary/follow-up-email) · [Monthly recurring revenue (MRR)](https://learn.ynteractive.com/content/glossary#monthly-recurring-revenue) · [Prompt engineering](https://learn.ynteractive.com/content/glossary) · [Training data](https://learn.ynteractive.com/content/glossary) · [Upsell](https://learn.ynteractive.com/content/glossary#upsell) · [Claude Projects](https://learn.ynteractive.com/content/glossary#claude-projects) · [Artificial intelligence (AI)](https://learn.ynteractive.com/content/glossary#artificial-intelligence)

[The full AI glossary](https://learn.ynteractive.com/content/glossary)

## Related prompts

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