How to Train Copilot to Write Emails That Actually Sound Like You

Every AI-drafted email sounds like AI. The sentences are clean. The structure is logical. The tone is polished but somehow generic. Your colleagues can’t always put their finger on why it reads as off, but they feel it.

The reason is simple: by default, Copilot doesn’t know how you write. It produces professional email in its own style, which is not your style. This is fixable, and the fix is straightforward once you know it.

Why most Copilot emails don’t sound like you

Copilot generates email from your prompt plus its general understanding of professional communication. It doesn’t know that you keep subject lines short, or that you always open with context before the ask, or that you close with “let me know” instead of “please don’t hesitate to reach out.” It doesn’t know your level of formality, your preferred sentence length, or how direct you are with people you know well.

Without that information, it defaults to a kind of averaged professional register. Competent, but not yours.

The fix is giving Copilot your voice as reference material. And the best source of that reference material is already sitting in your Outlook: your sent mail.

Step 1: Pull 2 months of sent mail into Copilot

Open Copilot (in Outlook, Teams, or the M365 Copilot app) and paste in a sample of your sent emails. Aim for 8 to 12 emails from the last couple of months, covering different types: a quick reply, a longer explanation, a request, a follow-up, a message to someone senior, a message to a close colleague.

You don’t need to include anything sensitive. Subject line + body is enough. You can anonymize names if you prefer.

The sent box is the right source because it reflects how you actually write when you’re not thinking about it. That authentic register is exactly what you want Copilot to learn from.

Step 2: Ask Copilot to analyze your writing patterns

Once you’ve pasted the emails, ask Copilot something like:

“Based on these emails I’ve written, identify my writing patterns. Look at things like: sentence length, formality level, how I open and close emails, how direct I am, my typical paragraph length, whether I use bullet points, and any phrases or expressions that appear repeatedly.”

Copilot will produce a detailed breakdown. Something like: “You tend to open with a one-sentence context statement before making your ask. Your sentences average 15 to 20 words. You use a formal but warm tone with senior contacts and a more casual register with peers. You almost never use bullet points in emails.”

Read through it. Correct anything that’s off. Add anything it missed.

Step 3: Turn that analysis into a tone guide

Now ask Copilot to convert the analysis into a set of instructions:

“Turn that into a set of clear writing instructions I can give you when drafting my emails, so you write in my voice.”

The output will be something like:

• Open with a single context sentence before the main request
• Use short paragraphs, one to three sentences each
• Keep the tone professional but direct, not corporate
• Close with “let me know” or “happy to chat” rather than formal sign-offs
• Avoid exclamation points except in casual contexts
• Match the level of formality to how well I know the recipient

Step 4: Save it in your Outlook draft instructions

In Microsoft 365 Copilot for Outlook, you can save custom instructions that apply every time Copilot drafts an email for you. Paste your tone guide there.

From that point on, when you ask Copilot to draft an email, it uses your instructions as the baseline. The prompts still matter — Goal, Context, Source, Expectation still apply — but the tone is now anchored to how you actually write.

You’ll still want to review and adjust. Copilot isn’t perfect, and first attempts will sometimes feel slightly off even with good instructions. Refine the tone guide over time as you notice patterns in what it gets wrong.

Bonus: Store reusable templates in instructions too

Draft instructions aren’t only for tone. You can also include templates for email types you write repeatedly: a standard meeting request, a follow-up after a proposal, a check-in with a client who’s gone quiet.

Store the skeleton in your instructions and ask Copilot to fill in the specifics. You get the structure and the voice with a single prompt.

This is the part most people don’t know exists. By the time I covered it in workshops, email was already 40 minutes into the session and people were starting to see what Copilot could actually do. The instructions feature was the one that got the most “wait, seriously?” reactions.

The underlying principle

Your sent box is the best training data for your own voice. You’ve been writing yourself for years. That signal is already there. Copilot just needs someone to point it at the right place.

Once the tone guide is in place, the AI-written email problem mostly goes away. The emails still need your review, but they start from somewhere that sounds like you.

This is the kind of thing I cover in Copilot adoption workshops. See how I work with teams →