Copilot drafts your emails, but the style is a compromise. With custom instructions you explain your way of writing once and from then on you get drafts that sound like you.
What are custom instructions?
Custom instructions are permanent rules that you give Copilot once, for example your preferred tone, the length you want or a particular greeting. As soon as you have saved them, Copilot applies these settings automatically to your drafts.
Think of it as a briefing for a new assistant: instead of explaining how you write with every request, you say it once and it remembers.
At a glance
- Set up once, active permanently
- Applies to drafts that Copilot writes for you in Outlook
- Written in your own words: tone, length, greeting, sign-off, language
- Can be changed at any time
What you need
- A suitable licence: Microsoft’s instructions mention a Copilot licence for work or a Microsoft 365 subscription. To find out what your organisation has switched on, read the article on unused Copilot licences or ask your IT team.
- The new Outlook for Windows, Outlook for Mac or Outlook for iOS and Android. Microsoft’s instructions do not list classic Outlook for Windows.
Think for a moment: in which version of Outlook does Microsoft not list draft instructions?
Step by step: how to set it up
- In the new Outlook, open the drop-down next to the Copilot icon and choose Settings.
- Select Draft Instructions.
- Turn on «Use custom instructions when drafting email» and type your instructions into the box.
- Select Save.
That’s it. From now on Copilot in Outlook works to your rules, without you having to explain anything with every draft. The steps are also in Microsoft’s instructions.
Check what Copilot produces
Now let Copilot draft a reply to an email. Then check whether the draft matches your style. Not happy yet? Keep adjusting your instructions, it is worth it.
What you can put in the instructions
There is no set structure. You can simply describe in natural language how you want to communicate.
Tone
«Always use a friendly but professional tone. Avoid overly formal language.»
Length
«Keep emails short, no more than 5 sentences for routine messages, more detailed only for complex topics.»
Greeting
«Start internal emails with ‹Hi [name]!› and external ones with ‹Dear [name]›.»
Sign-off
«End emails with ‹Kind regards, [your name]› and do not add a separate closing sentence, my signature takes care of that.»
Language
«Write in German unless the original email was in English, in which case reply in English.»
Exercise
Which lever is this?
5 tips for better results
- Be specific: «Friendly» is vague. «Use the first name, keep the tone warm and end with a question», that is precise.
- Also say what Copilot should not do: for example «Do not use ‹as discussed› or ‹per my last email›.»
- Define length in measurable terms: instead of «short» go with «no more than 3 sentences for standard messages.»
- Test and refine: after saving, try a few drafts and adjust the wording if needed.
- Keep them current: new role, new style? Just go back into the settings and update your instructions.
Not sure which custom instructions to add?
This trick helps if you have a Microsoft 365 Copilot licence. Only with it does Copilot access your work data such as emails, chats and files. Without that licence, Copilot Chat only works with files you upload, according to Microsoft (Microsoft’s overview).
- Open a new chat in Copilot
- Run this prompt: «Analyse the emails I have sent over the last few weeks and derive custom instructions for Copilot in Outlook from them that I can copy across word for word.»
- Copy the result into the custom instructions
- Test and refine it. Check the suggestion critically before you adopt it.
Quick check
Three questions to take away
Conclusion
Custom instructions are one of the most useful and least known features of Copilot in Outlook. Setting them up takes two minutes, the effect is permanent. Open the Copilot settings in Outlook now, write three sentences on tone, length and greeting and let Copilot draft your next reply.
«Say once what you want. Copilot writes it that way from then on.»