Outlook Copilot is fast at summarizing a long thread and drafting a reply. It is also good at pulling the wrong context: another conversation you can open, a file Work IQ can see, a side thread about a vendor you were not going to mention.
The danger is the adjacent email, not the blank compose box.
This lesson is one real thread you will answer. Summarize it. Draft the reply inside that thread. Then ask what else might have walked in.
Core principles
- Stay in the thread you will send. Do not draft a vendor reply from a Chat that still has the internal thread in view.
- If Work IQ is on, assume Copilot can use mail you can already open. Turn it off or attach only this thread when the audience is outside the project.
- Tone coaching is useful. Fact invention in a reply is a send-button problem.
- Decline and delay are still yours. Copilot should not accept a meeting or promise a date you did not give it.
Related: Which Copilot — oversharing inside Graph
Check yourself
What is the main oversharing risk when Copilot drafts an Outlook reply?
Chats stay yours. The leak is you sending a draft that used the wrong source. Stay in the thread. Trace the sentences.
Do this in Copilot
Open the thread you owe a reply on. Draft in that thread. List any sentence that came from somewhere else. Delete those before you send.
Run this in the Outlook thread, or paste only this thread into Chat.
Reply from this thread only
Summarize this email thread in five lines: decision, open question, who last spoke, what they asked me, deadline if any. Then draft a reply to [PERSON] that answers only what is in this thread. Audience: [INTERNAL / VENDOR / CLIENT]. Do not use any other mail, files, or meetings. If you would need another source, write [Need source] instead of guessing. Do not promise a date I did not give you. Keep it under 150 words.
Did you run this in Copilot? Mark complete when you have tried it.
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