AI email writing: how to draft better emails with AI and check them

When is AI useful for writing emails?

AI is most useful for emails where you know what needs to be said but drafting it takes effort: a structured update, a polite chase, a reply that has to cover several points from a long thread, or a message you need to make shorter or firmer. In those cases the facts and the decision are yours, and the tool handles arrangement and wording.

It is least useful, and riskiest, when the email itself is the decision. A message that commits the company to a refund, a date, a price or a contractual position needs a person to decide the substance first. If you ask the tool to work out what to offer, it will offer something, and it may be something nobody authorised.

What should you tell the AI before it writes an email?

Tell the tool who the email is for, why you are writing, the facts it may use, the single action you want from the reader and any limits on tone and length. Everything you leave out, the tool fills with a guess. The guesses are where most AI email problems come from: invented apologies, made-up dates and offers nobody approved.

What does a good AI email prompt and review look like?

Here is a worked example from a fictional 18-person furniture retailer, Brightwell Interiors. A customer, Ms Okafor, has emailed asking where her sofa is. The supplied facts: the order was due to ship on 3 November; the warehouse has flagged a fabric shortage; the supplier has not yet given a new date; the support lead can offer to switch fabric or cancel with a full refund; no compensation has been approved.

Weak prompt: Write a reply to this customer saying sorry her sofa is late. Typical result: Dear Ms Okafor, we are so sorry for the delay. Your sofa will now arrive on 14 November, and as a gesture of goodwill we have applied a 10 percent discount to your order. The date and the discount are both invented. If that email is sent, the company has made two promises it cannot keep.

Better prompt: Draft a short, warm reply to a customer asking about a delayed sofa. Facts you may use: original ship date 3 November; delay caused by a fabric shortage at our supplier; no new date yet; options are to switch to an in-stock fabric or cancel for a full refund. Do not give a new date. Do not offer a discount or compensation. Ask her which option she prefers, or whether she would rather wait for an update. Under 120 words.

Reviewed draft: Dear Ms Okafor, thank you for checking in, and I'm sorry for the wait. Your sofa was due to ship on 3 November, but our supplier is short of the fabric you chose and has not yet confirmed a new date. You have three options: switch to a fabric we have in stock, cancel for a full refund, or wait and we will update you as soon as the supplier confirms. Just reply with whichever suits you best. The reviewer checked the ship date against the order, confirmed the two options with the support lead and confirmed nothing else was promised.

How do you use AI to reply to a long email thread?

Use AI to summarise the thread first, check the summary, then draft the reply from the checked summary. Going straight from a long thread to a reply in one step hides what the tool decided was important. A separate summary step lets you see whether it has dropped a question someone asked or misread who agreed to what.

A useful summary prompt: List every open question in this thread, who asked it and whether it has been answered. Then list any commitments made, with the person who made them. Quote the relevant line for each. Check that list against the thread, especially commitments, because tools often turn a suggestion into an agreement. Then ask for a reply that answers the open questions in order.

How do you change the tone of an email with AI?

Ask for a specific change and say what must not change. Make it friendlier is vague; keep every fact and the deadline exactly as written, remove the two sentences of apology, and make the request in the first line is precise and checkable. After any rewrite, compare the facts in the new version against the old one. Tone edits are a common place for a date or a condition to drift.

Two tone tasks are worth practising because they are hard to write by hand: declining politely and being firm without being rude. For a decline, give the tool the reason you are willing to share and the alternative you can offer. For a firm chase, give it the original request, the date it was due and the consequence you are prepared to state. Then read it as the recipient would.

How do Copilot in Outlook and Gemini in Gmail fit in?

Built-in assistants such as Copilot in Outlook and Gemini in Gmail are the same idea inside your inbox, and the same rules apply. Microsoft's support page describes drafting by opening a new message, choosing the Copilot option, typing a prompt and generating a draft, with options to adjust length and tone or regenerate, then keeping, editing and sending it. The page also notes that a draft's sensitivity label may change if the generated output has a higher sensitivity level.

Google's help page for Gemini in Gmail says it can create new emails or refine existing drafts for tone and clarity, requires an eligible Google Workspace or Google AI plan, and warns that Gemini features may suggest inaccurate or inappropriate information. Availability depends on your plan and your administrator's settings, so check with whoever manages your accounts. A built-in tool is not safer by default; it is just closer to the send button.

What should you never put into an AI email tool?

Do not put in information your company has not approved for that tool. That usually means no customer personal data beyond what the approved plan allows, no passwords or account numbers, no confidential client material and nothing covered by a non-disclosure agreement unless your policy says the tool is cleared for it. When in doubt, replace names and identifiers with placeholders such as [customer] and [order number], draft, then fill them in yourself.

Be particularly careful with forwarded threads. A thread you paste in for summarising may contain someone else's personal details or a confidential attachment quoted further down. Trim it to the part you need. The small-business AI policy guide covers how to write these rules down.

What should you check before sending an AI-drafted email?

Read the whole email as the recipient, then check every fact against its source. The list below takes a minute and catches most problems.

When should you not use AI to write an email?

Write it yourself when the message is personal, sensitive or legally significant. A condolence note, a difficult performance conversation, a reply to a formal complaint or grievance, a message to a regulator or a negotiation where every word has a cost are all poor fits. The recipient may reasonably expect the words to be yours, and a generated phrase that misjudges the moment does damage that editing cannot fully repair.

It is also often slower to prompt than to type a two-line reply. AI email writing earns its place on longer, structured messages, not on every quick answer. This guide is about everyday work email; for broader business documents, see the guide to AI writing for business.

Sources and scope

Microsoft Support, Draft an email message with Copilot in Outlook, accessed 16 October 2026 ↗

Gmail Help, Collaborate with Gemini in Gmail, accessed 16 October 2026 ↗

NIST, AI 600-1: Generative AI Profile, July 2024 ↗