How to use AI to write customer emails that still sound like you

You asked ChatGPT to answer a customer who wanted to know if the blue mug comes in a bigger size. It came back with "I hope this email finds you well" and "Thank you for reaching out regarding your inquiry", and signed off "Warm regards". You've never written "warm regards" in your life. Your customers know how you write, and this wasn't it.

AI can save you real time on customer emails, but only if you stop asking it to write the email and start asking it to tidy yours. Give it the facts in your own rough words, plus a short note about how you write and what you never say, and it will send back something that sounds like you on a good day. The rest of this post gives you that note to copy, a prompt for everyday replies, and the jobs where you're better off writing it yourself.

Why AI emails sound like nobody

When you ask for "a reply to this customer", the AI has nothing to go on but the most average version of a polite business email. So you get the most average version: the stock opener, the formal sign-off, the American spelling, three sentences where one would do.

A cleverer prompt won't change that much. What changes it is giving the AI two things it can't guess: what you actually want to say, and how you say things.

Write a voice card once

A voice card is a short note about how you write. You write it once and paste it in, or save it so the AI uses it every time.

Copy this and fill it in:

How I write to customers: - I run [shop], a [what you sell] shop in [place]. I sign off as [first name]. - I write short emails. Two or three short paragraphs at most. - I'm friendly and plain. I use contractions. UK spelling. - I start with "Hi [name]," and end with just my name. - I never write: "I hope this email finds you well", "reach out", "inquiry", "warm regards", "we apologise for any inconvenience", exclamation marks. - When I don't know something, I say so and say when I'll find out. Two emails I've sent that sound like me: [paste one] [paste another]

The "never write" line does more work than anything else on the card. Read back a few AI drafts and add every phrase that made you wince. The two real emails matter too: they show the AI your rhythm better than any description of it.

Before you paste real emails in, take out anything personal about the customer: their name, address, order details. You're showing the AI your writing, not their information.

Save it so you don't paste it every time

Both of the big assistants let you save standing instructions.

• ChatGPT. OpenAI's help page on custom instructions says they "allow you to share anything you'd like ChatGPT to consider in its response" and that they're "available on all plans". On the web, go to Settings, then Personalization, and put your voice card in the Custom Instructions field.
• Claude. Anthropic's guide to Claude's personalisation features describes profile instructions that are "applied to all of your conversations with Claude", and project instructions that "only apply to chats within that project". A project just for customer emails keeps your voice card separate from everything else you use it for.

One thing to know: the same OpenAI page says information from your use of custom instructions "will also be used to improve model performance" unless you opt out. Another reason to keep customer details out of the voice card. Our post on whether it's safe to put customer details into ChatGPT covers the rest.

A prompt for everyday replies

Each time a customer emails, give the AI the facts in your own rough words. Don't make them sound nice. That's its job.

Reply to this customer using my voice card. What they asked: does the blue mug come in a bigger size. What I want to say: no, but the green one does and it's nearly the same blue. Link: [link]. Happy to send a photo of both side by side. Back in stock end of month if they'd rather wait for a big blue one, which I'm thinking of making. Keep it under 80 words.

The rough facts are where your voice really comes from: the detail about sending a photo, the honest "I'm thinking of making one". The AI can only polish what you give it.

Read it aloud before you send

Every time, before you press send, read the draft out loud. If there's a sentence you wouldn't say to that customer at the counter, cut it or change it. It takes twenty seconds and it catches the things the voice card missed.

Check the facts too. AI will sometimes fill a gap with something that sounds right: a delivery date, a size, a promise you didn't make. If it's in the email and you didn't tell it, check it or take it out.

When to write it yourself

AI drafts are good for the everyday: stock questions, delivery times, thank-yous, "yes we can gift wrap that". Write it yourself when:

• Someone's upset. An apology needs to sound like a person who's sorry, and a polished AI paragraph rarely does.
• It's personal. A regular whose dog died, a thank-you to a long-standing wholesale buyer.
• It's three lines. By the time you've explained it, you could have written it.

Say you sell handmade candles

Say you get fifteen emails a week asking about scents, burn times and delivery. You write a voice card one evening, with your two favourite replies and a "never write" list of six phrases. After that, each reply is: paste their question, jot what you want to say in a line or two, read the draft aloud, fix one word, send. The emails still sound like you, and the ones that matter, the complaints and the regulars, you still write by hand.

The candle shop is made up for this example. Your own two best emails are the ones to use.

Where Workden fits

The slow part is often not the writing. It's finding out what you need to say: what they ordered last time, what you told them in March, whether their parcel has shipped.

Workden connects to the ChatGPT or Claude you already use. Your own assistant "answers from your records and drafts the reply for you", so the draft starts from the customer's history rather than whatever you remember to paste in. And "nothing is sent or changed until a person approves it". Your AI subscription isn't included; as the pricing page puts it, "You bring the ChatGPT or Claude you already have." Your voice card still does the same job there.

You can try it free for 14 days.

Questions shop owners ask

Can customers tell if an email was written by AI?

Often, when it's the default AI style. A voice card, your own facts and a read-aloud check before sending close most of the gap.

Is it OK to use AI to reply to customers?

For everyday replies, yes, as long as you check the facts and it sounds like you. Keep personal details out of the general chat apps, and write the sensitive ones yourself.

Which is better for writing emails, ChatGPT or Claude?

Both can save standing instructions and work well with a voice card. Try the one you already pay for before buying another.

Sources

Checked 22 October 2026.

• OpenAI Help: ChatGPT custom instructions
• Claude Help: Understanding Claude's personalisation features
• Workden features
• Workden pricing