Let ChatGPT copy your writing style, then test it properly
ChatGPT has a setting called Reference my writing style. When I switched it on, ChatGPT said it "uses your chats and Library files to write in your style." I asked ChatGPT Work for the same short email with the setting off, then on. The difference was small. Here's how to set it up and how to test it on your own emails.
What you need
ChatGPT on the web. OpenAI documents writing style for ChatGPT Work on the web, and that's where I tested it.
Nothing to connect. The setup window lists email, messaging and document apps under "Connect apps to improve writing (optional)". Which apps you see depends on your account and workspace.
The setup (on my account, 27 Oct 2026)
In ChatGPT on the web, open Settings > Personalization.
Under Writing, turn on Reference my writing style. Its description says "Let ChatGPT use your chats, Library files, and connected apps to write in your style."
A window opens: "Writing style is personalized. ChatGPT uses your chats and Library files to write in your style." Connecting apps there is optional. Close the window and the switch stays on.
Ask Work for an email, message or document.
OpenAI's help page describes another route: open Set up writing style (https://chatgpt.com/?surface=work&writing_style=setup), connect apps, then select Use writing style. My account had no Use writing style button, and the switch in step 2 did the job. If your screen matches OpenAI's page, follow that instead.
The test
Ask for the same email twice: once with the setting off, once with it on. Then compare the two drafts line by line.
My test used a sample with a made-up name:
Write a short email to Dana: we need to push the site visit to Thursday.
Subject. Setting off: "Rescheduling the Site Visit". Setting on: "Site visit".
The ask. Setting off: "Please let me know if that works for you." Setting on: "Let me know if that still works for you."
The greeting and the first sentence came out the same. The one with the setting off came as an email card, the one with it on as plain text. A two-line email doesn't leave much room for style, so run the same test on a longer email before you trust it:
Write an email to [someone you write to often] about [something you need to send this week]. Make it as long as I'd normally write.
Run it with the setting off, then on, and put both drafts next to an email you wrote yourself. Keep the setting if the second draft is closer to yours.
To turn it off
Same switch: Settings > Personalization > Writing, then turn off Reference my writing style. OpenAI's page says the same: "open Settings > Personalization > Writing on the web and disable Reference my writing style."
The mistake to avoid
Judging it on one short email. My short test changed three small things. That tells you very little about how it handles the emails you write every week, so test it on those.