Best AI Email Reply Generators: 9 That Draft in Your Voice

Inside your mail client, or a new place to read mail

You open a thread and the reply is already sitting there, sounding like you, ready to tweak and send. That's the job. There are two ways to get that, and they ask very different things of you.

The first is a drafter that plugs into the mailbox you've got. You keep Gmail or Outlook, your folders, your filters and your phone app, and the tool reads incoming mail and leaves a draft in the thread. Nothing about your day changes except that the blank reply box isn't blank any more. The second is a mail app that does the drafting itself. You move your reading and writing into it, and in return the drafts can draw on more than the email: your calendar, past threads, sometimes the web. That's a bigger move, and it only pays off if you'd like the app even with the AI switched off.

There's a third route that sits in between: a general AI agent you connect to your inbox and instruct to draft replies. It's the most flexible and the most work to set up, because you're describing the job yourself rather than switching on a feature someone else has tuned.

A reply generator isn't the same as an inbox assistant

The words get used loosely, so it's worth being clear. An inbox assistant sorts, labels, summarises and chases. A reply generator's whole job is the draft. Plenty of tools do both, but if the thing you hate is writing the answers, judge them on the drafts and nothing else. If what you really want is the triage, our guide to AI email assistants covers that wider job. And if you mostly write new emails from scratch rather than answering, AI email writers are the better fit, because they start from a prompt instead of a thread.

The other difference is timing. A writer waits for you to ask. A reply generator works ahead of you, so the draft exists before you've opened the message. That's what saves the time, and it's also why the voice matters so much: you'll see dozens of these a day, and if each one needs rewriting you've gained nothing.

Add-ons that draft in the Gmail or Outlook you already use

Fyxer

An inbox assistant that tidies your mail and leaves first-draft replies written in your own style, for people who'd rather not change mail apps.

Jace

Built as an email agent for Gmail and Outlook, it prepares replies from your email context and holds them for you to review.

Inbox Zero

If your past emails already say how you answer most things, this assistant sorts incoming mail and pre-drafts replies from that history.

MailDrafter

A small Gmail add-on that reads new mail and saves a reply draft grounded in your past conversations and your own FAQ, charged per reply.

MailMaestro

Formerly Flowrite, this Outlook and Gmail add-on builds responses from the thread and its attachments, and can write them in several languages.

Lindy

Teams wanting a general AI agent can point this one at an inbox and have it draft replies in their voice for approval.

Mail apps with the drafting built in

Superhuman

A fast email app whose drafting feature writes replies using your inbox, calendar and the web as context.

Shortwave

An AI-first email client whose agent organises, schedules, searches and writes from a plain prompt.

Spark

For anyone who wants one mail app across several devices, with replies drafted ahead of time by its built-in assistant.

The one-hour test with your own mail

Demo videos always show the easy email. Yours won't be. So give any shortlisted tool a real hour before you pay.

Start by connecting it to your actual mailbox, not a clean test account. A drafter with nothing to learn from will sound like everyone else, and you'll judge it unfairly. Then pick twenty recent threads you've already answered: a few quick yes-or-no ones, a few awkward ones (a late payment, a no, a price question), and a few from people you're close to. Let the tool draft for each, and put its draft next to what you really sent.

Score each one simply. Could you send it with a word or two changed? Does it get the facts right, or does it promise a date, a price or a meeting you never agreed? Does it sound like you on a good day, or like a polite stranger? If it passes on the quick ones and fails on the awkward ones, that's normal, and it's still useful. If it fails on the quick ones, move on.

Last, check what it did to your mailbox. Where did the drafts land? Did it label or move anything you didn't ask it to? Can you switch it off in one click? You'll live with this thing every day, so the boring answers matter.

How the bill is worked out

Three pricing shapes run through this category, and the right one depends on how much mail you answer rather than on the headline number.

Per seat is the most familiar: a flat monthly fee for each person, whatever their volume. It suits someone who answers a lot of mail every day, and it gets expensive across a team where only a couple of people are heavy users. Credits are common with the agent-style tools: your plan comes with a monthly allowance, and each piece of work the agent does uses some of it. That's fair when your volume swings, but read what a credit buys, because a busy week can run the allowance down faster than you'd guess. Pay per reply is the rarest shape here, with one tool on this list using it: you're charged for each draft written, and in one case a little more when attachments are involved, so a quiet inbox costs very little and a flooded one costs a lot.

Among the tools that publish a price, paid plans run from about ten dollars a month per user to about fifty dollars a month for a credit-based team plan, and the per-reply option charges around a quarter of a dollar for each draft. Superhuman and MailMaestro don't publish a price on the pages checked for this list, so check each pricing page on the day you buy.

Do you make AI email reply generators? Tool makers can ask to be considered for a featured place on this list.

Mistakes that make the drafts worse

Judging the tool in its first hour is the commonest slip. Most of these draft from what you've written before, so they need your real history to work with. Give it a week of normal use before you decide it can't write like you.

Letting it answer the mail it shouldn't comes close behind. Complaints, anything legal, anything about money owed, anything emotional: you want to write those yourself, or at least read the draft twice. If the tool lets you exclude certain senders or labels, use that on day one.

Then there's the knowledge gap, which people tend to forget. A drafter only knows what's in your mail and whatever else you've connected. If the answer to a common question lives in a document it can't see, it'll guess, and guesses in a confident tone are worse than a blank box. The tools that let you feed in your own FAQ or past conversations handle this better, so it's worth a few minutes setting that up.

And don't switch mail apps just for the AI. If you'd hate the app with the drafting turned off, you'll hate it in a month. If you're already shopping for a new client, our roundup of Superhuman alternatives compares the wider field.

Draft only, or allowed to send

Several of the tools here describe their output as drafts waiting for your review, and for most people that's the right setting. A draft costs you a glance. A wrong email sent in your name costs you a client's trust, and you can't take it back.

Even the agent-style tools on this list describe their replies as drafts held for your approval or review. Whatever you pick, read how it handles drafts before you connect your main inbox, so you know exactly what it'll do with your mail on day one.

Which type to pick

If you like your current inbox and want replies waiting in it, choose a Gmail or Outlook add-on that drafts for review. If your volume is low or uneven, look for one that charges per reply or by credits so a quiet month stays cheap. If you were going to change mail apps anyway, try one of the apps with drafting built in and judge the app first, the drafts second. And if your replies depend on information outside email, such as a price list or a policy page, a general AI agent you can feed your own material is the type that'll cope best, as long as you're happy to spend an afternoon setting it up.

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Frequently asked questions

Will the person I'm emailing be able to tell a reply was AI-drafted?

Not from the email itself if you edit it before sending, because it goes out from your own account like anything else you write. They'll notice the tone, though, so the drafts that read like you are the ones worth keeping.

Do these tools need access to my whole mailbox?

To draft replies in context, they need to read the incoming mail and usually your past threads, so expect a broad permission request when you connect. Read what each vendor says about how it stores and uses your email before you agree. If it's a work account, check your company's rules first.