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No More AI-Speak in Your Emails: How to Train Copilot on Your Style
“Since I set up your Custom Instructions, I actually enjoy writing emails with Copilot in Outlook!” That was the feedback from a workshop participant. Not my words. That’s exactly the goal: Copilot should feel like you, not like a machine.
The Problem with AI-Generated Emails
You know the feeling? You let Copilot draft an email, and the result sounds like AI right away: “I hope this email finds you well.” “Please do not hesitate to reach out.” Formulas nobody would choose to write on their own.
That’s not because Copilot is bad. It’s because it doesn’t know your style. The solution is Custom Instructions. You give Copilot a clear description of how you communicate, once, and it sticks to it.
Why Custom Instructions Are a Game Changer
I use it myself. No more “I hope this email finds you well.” My emails sound like me again: direct, clear, in German, and without empty phrases.
You don’t have to write Custom Instructions yourself. There’s an analysis prompt that does it automatically. It reads your most recently sent emails in Outlook and creates a profile of your writing style from them. The result is a ready-made set of Custom Instructions that you can paste straight into Copilot.
The result is built so you can adjust and refine it yourself at any time.
The Analysis Prompt
Copy the following prompt into Copilot. Use the newest reasoning model for this (GPT-5.5 Deep Reasoning, or whichever is the most current one) via the Model Switcher in Microsoft 365 Copilot. This “deeper thinking” delivers noticeably better results than the standard model.
Important: This only works with a Microsoft 365 Copilot Premium license, and only in the Work tab (not with the Basic license, and not in the Web tab either, since that doesn’t have access to the mailbox).
We're working together to improve emails generated by Copilot.
Step 1: Analyze my emails sent in Outlook over the last three months and use them to create a personal profile of my writing style, so an AI can adopt my style precisely and make email drafting easier for me.
Take into account:
- General tone (friendly, direct, formal, collegial)
- Typical length and content structure
- Frequently used words, phrases, and expressions
- Technical depth
- Concrete examples of greetings, introductions, main sections, and closings
Step 2: Also research typical elements that make emails sound artificial
or AI-like.
Result: Then create a set of Custom Instructions for Microsoft Copilot in Outlook in English, formatted as a code block in Markdown as a Code Interpreter element. Include the following:
- General instructions so emails sound as human and natural as possible
- My personal tone, sentence structure, and typical phrasing from Step 1
- Explicit rules that prevent the AI-typical clichés from Step 2Important: If you often write mixed emails (German/English), it’s better to set up your instructions in English. Use the prompt at the very bottom for that. It’s also my original prompt, the one that’s gotten me the best results.
Putting the Custom Instructions to Work
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Open Copilot in the Microsoft 365 Work tab
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Switch to the newest reasoning model in the Model Switcher (e.g., GPT-5.5)
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Paste in the prompt and start the analysis
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Copy the generated Custom Instructions
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In Outlook, go to: Settings > Copilot > Custom Instructions > Paste
From now on, Copilot writes emails in your style.
Addendum: Analysis Prompt in English
We're working together to improve emails generated by Copilot. Step 1: Analyze my emails sent in Outlook over the last three months and use them to create a personal profile of my writing style so that an AI can accurately adopt my style and make my work easier by formulating emails. Take into account: - general tone (friendly, direct, formal, collegial), - typical length and content structure, - frequently used words, phrases and phrases, - technical depth, - concrete examples of greetings, introductions, main parts and conclusions.
Step 2: Additionally, research typical elements that make emails sound "AI-like." Result: Then create a set **Custom Instructions for Microsoft Copilot in Outlook** **in English**, formatted **as a Code Interpreter Element in Markdown**. Include in it: - general instructions to make emails sound as human and natural as possible,What This Means for Your Workday
The full walkthrough and context are already in this article. If you want to apply it to your own setup, coaching for individuals is the right place to start.
