Copilot in Outlook: reply drafts and Coaching

Of every Copilot surface in Microsoft 365, Outlook is the one where the value shows up in the first week and the risk shows up in the first month. Draft with Copilot writes replies; Coaching by Copilot critiques the ones you wrote yourself. Both are shipped and stable. This guide covers what they actually produce, the controls users have, the client and mailbox constraints that generate most of the tickets, and the two habits that stop a generated reply from embarrassing someone.

Draft with Copilot

In a new message or a reply, the Copilot button (or the prompt box that appears in an empty body) takes an instruction — "decline politely and suggest next Thursday," "say yes and ask for the invoice number" — and produces a full reply. In a reply, Copilot reads the thread, so "answer their three questions" works without you restating them. It also offers quick reply suggestions on some threads: one-click draft starters based on what the thread seems to need.

After a draft appears, the controls that matter:

• Tone — direct, neutral, casual, formal, and make it a poem (which exists and which someone will use on the CFO). Neutral is the sensible default for most business mail.
• Length — short, medium, long. Copilot defaults to more words than an email needs. Short is usually right; most replies in corporate mail are three sentences.
• Regenerate and free-text refinement — "mention the SLA," "remove the apology."

What comes out is competent, polite, and slightly over-explained. It reads like a good junior colleague's reply: nothing wrong, nothing memorable. That's fine for 80% of mail.

Where drafts go wrong

It answers the thread, not the situation. Copilot knows what's in the emails; it doesn't know that the sender is a difficult customer, that the "quick question" is really an escalation, or that you already agreed something on a call. A draft that's technically responsive can be politically wrong.

It commits you to things. "Suggest next Thursday" can become "I'm free all day Thursday." Read every sentence with a date, a price, or a promise in it.

It doesn't check facts. If someone asks whether the contract renews in March, Copilot's draft may confidently say yes based on nothing. It is not looking at the contract unless you attach it or reference it.

Thread context cuts both ways. Copilot may pull in a detail from earlier in a long thread that you'd deliberately dropped. On sensitive threads, read the whole draft before sending — obvious advice that's ignored daily.

Sensitivity labels and the reply. A generated reply inherits the label of the message it's replying to, as any reply does. Copilot doesn't downgrade labels, but it also doesn't warn you that you're about to answer a Confidential thread with an external recipient added — that's Outlook's normal label and DLP behaviour, not Copilot's.

Coaching by Copilot

Write a reply yourself, then choose Coaching by Copilot. Instead of rewriting, Copilot returns feedback in three areas — tone, reader sentiment (how the recipient is likely to feel), and clarity — with specific suggestions you can apply or ignore. Your text is untouched unless you click to apply a suggestion.

This is the better feature for anyone who writes fine but writes too fast. It reliably catches: emails that read as curt when you meant efficient; passive-aggressive phrasing you didn't notice; buried asks; unexplained acronyms; and replies that don't actually answer the question that was asked. It's less good at anything domain-specific — it won't tell you the technical answer is wrong — and it can be a little precious about directness in cultures where direct is normal.

Practical use: run Coaching on anything going to a customer, an executive, or someone you're annoyed at. Skip it on the "thanks, received" replies.

Requirements and the tickets they generate

• Licence. Microsoft 365 Copilot. The free Copilot Chat surface does not draft inside Outlook.
• Client. New Outlook for Windows, Outlook on the web, Outlook for Mac, and Outlook mobile all support it. Classic Outlook for Windows supports Copilot too, but on current builds in the supported update channels — a tenant lagging on the Semi-Annual channel is the usual reason "Copilot isn't showing up."
• Mailbox. Copilot works against the user's primary mailbox. Support for shared mailboxes and delegate access has been arriving in stages; check the current state before promising a shared-inbox team that Copilot will draft their replies. This single limitation is the most common "Copilot doesn't work" ticket from customer-service teams.
• Account type. Work or school accounts with Exchange Online mailboxes. On-premises mailboxes in a hybrid tenant don't get Copilot in Outlook.
• Meeting invitations and calendar items have their own Copilot features (summaries, agenda drafting) that behave slightly differently from mail drafting.

Admin controls

There's no separate "Copilot in Outlook" switch. The lever is the Copilot licence assignment and the tenant-level Copilot settings in the Microsoft 365 admin center (web grounding, feedback, the newer per-app controls). If you need to keep Copilot out of a specific team's mail, don't assign the licence — there is no per-mailbox policy that's more granular than that.

Audit records for Copilot interactions in Outlook land in the unified audit log like other Copilot activity, and Purview's Copilot-specific reporting covers prompts and responses at the level the tenant's retention settings allow.

What to tell users

Two habits: read the draft as if the recipient sent it to you, and use Coaching on anything that matters. Then two facts: it defaults to too long (pick short), and it doesn't know anything outside the thread unless you put it there. That's the whole training session; the rest people learn by doing.