Short answer: an AI that writes email replies in your own voice studies emails you have already sent. It picks up your greetings, sentence length and level of formality, then drafts new replies in that style. In November 2026 the tools that do this automatically inside Gmail and Outlook are Jace, Fyxer and Superhuman's Email Assistant. Each one leaves a ready draft in your inbox for you to edit and send. Gemini in Gmail and Copilot in Outlook also write replies, but only when you ask, and you pick the tone each time. Jace drafts in a "Copy Your Voice" style by default, uses the full thread and its attachments, and sends nothing unless you turn on auto-send.
Vendor facts on this page come from each vendor's own site, opened on 9 November 2026 and linked at the end. Jace facts come from Jace's docs. We make Jace.
Which AI tools draft replies in your voice
| Tool | Learns your style from | Drafts without being asked | Works in | Price, billed yearly |
|---|---|---|---|---|
| Jace | Past emails it picks during setup, similar past replies, a writing example you can edit, and a voice preset | Yes, for the labels you choose, such as Needs Reply | Gmail and Outlook (drafts land in your Drafts folder) | $20 per user per month, $25 monthly |
| Fyxer | Your past emails, per Fyxer | Yes, on paid plans | Gmail and Outlook | $37 per person per month, $49 monthly |
| Superhuman Email Assistant | Emails you have already sent, per Superhuman | Yes, every message that needs a reply gets a draft | Gmail and Outlook | $12 per member per month, $15 monthly |
| Gemini in Gmail | Your prompt ("Help me write") | No, it drafts when you ask | Gmail | Included in Google Workspace and Google AI plans |
| Copilot in Outlook | Your prompt and a tone you pick ("Draft with Copilot") | No, it drafts when you ask | Outlook | Needs a Microsoft 365 Copilot licence |
For prices across nine tools, see how much an AI email assistant costs.
How AI voice matching works
Voice matching is an instruction plus examples. The assistant gives the model some of your past sent emails and says "write the reply the way this person writes". The model copies what it can see: how you open, whether you use first names, how long your sentences run and how you sign off.
The examples decide the result. If the samples are short internal replies, client drafts come out too casual. If the samples are formal proposals, a quick "sounds good" turns into three paragraphs. Good tools pick examples similar to the email you are answering. That is why a reply to a client can sound different from a reply to a colleague.
Voice is the easy part. A draft that sounds like you but gets the facts wrong is worse than a stiff one. The bigger question is what the AI reads before it writes: the last message only, or the full thread, the attachments and your calendar.
How Jace drafts in your voice
Jace builds your style from three sources, set in Settings → Writing Style (Writing style docs):
- Past replies. During setup Jace picks a few of your past emails as a writing example. When it drafts, it also pulls up similar past replies and imitates them.
- A writing example you control. You can edit the example or paste up to about 2,500 characters of your own emails. Jace's docs suggest 1 to 3 real emails that show your ideal tone, without signatures.
- A voice preset. Copy Your Voice is the default. Polite & Professional, Crisp & Concise and Warm & Upbeat are there when you want a different register.
Before it writes, Jace reads the whole thread and its attachments, checks your calendar when an email asks for a meeting, and follows your rules and signature (Drafting docs). The draft goes into your normal Gmail or Outlook Drafts folder, so you can send it from your phone's Gmail or Outlook app too. If a draft needs changes, ask in plain English ("shorter, and confirm Thursday") and Jace updates the same draft instead of making a new one.
Jace drafts automatically for the labels you choose. Needs Reply is on by default. You can switch drafting off per label, and auto-send stays off unless you turn it on for a label after a warning. Setup guides: Jace for Gmail and Jace for Outlook.
How to make AI drafts sound more like you
These steps work in Jace, and most of them help in any tool that learns from examples.
- Give it your best emails, not your fastest ones. Pick replies to clients or partners that you would happily send again.
- Remove signatures and footers from samples. Jace adds your Gmail signature on its own, and Outlook signatures go in Settings.
- Write rules for habits it can't infer. "Always use first names" or "never promise a delivery date" are better as rules than as hopes (Rules docs).
- Edit drafts for a week before judging. Count the drafts where you change a word or two and the ones you rewrite. That ratio tells you more than any demo.
- Refresh the example after a role change. A new job or new clients usually means a new tone.
When a built-in assistant is enough
If you write a few replies a day and like to start each one yourself, Gemini in Gmail or Copilot in Outlook can cover you. That is doubly true if your company already pays for them. They draft when you click, and you set the tone each time. A separate assistant earns its price when you want drafts already waiting in your inbox for every email that needs an answer. It also helps when you work across both Gmail and Outlook. Our comparisons of Jace and Gemini in Gmail and Jace and Copilot in Outlook cover the details.
Jace is a good fit for people who answer their own client email, such as lawyers and consultants. It is not built for teams sharing one support inbox.
FAQ
Is there an AI that drafts Gmail replies automatically? Yes. Jace, Fyxer and Superhuman's Email Assistant draft replies in the background for emails that need an answer and leave them in your Gmail Drafts. Gemini in Gmail drafts only when you ask with "Help me write".
Can AI write emails that sound like me? Yes, if it learns from your sent emails. Jace uses past replies, a writing example you can edit and a voice preset. Fyxer and Superhuman say they learn from your past emails too.
How does Jace learn my writing style? During setup Jace picks a few of your past emails as a writing example. Later, when it drafts, it pulls up similar past replies. You can edit the example in Settings → Writing Style and choose a preset such as Copy Your Voice or Crisp & Concise.
Does Jace send replies without me? Not by default. Drafts wait in your Gmail or Outlook Drafts folder. Auto-send is an opt-in setting per label, shown with a warning, and you can turn it off at any time.
Does Jace train AI models on my emails? No. Jace's security page says it never trains AI models on your email content.
Does voice matching work in Outlook? Yes. Jace works with Outlook on Microsoft 365 and Outlook.com, and its drafts land in your Outlook Drafts folder. See Jace for Outlook.
Try it on your own sent mail
The 7-day trial drafts replies for your Needs Reply mail in Copy Your Voice, with auto-send off. Edit a week of drafts and see how close they get. Start your free Jace trial, or compare Jace's plans first.
Sources (checked 9 November 2026)
- Jace: Writing style, Drafting, Rules, Security, pricing
- Fyxer: AI email writer, pricing
- Superhuman: Email Assistant, plans
- Google: Collaborate with Gemini in Gmail
- Microsoft: Frequently asked questions about Copilot in Outlook
