The 10 Best AI Tools for Email Writing in 2027

How We Ranked These

Email writing is more than grammar correction, so the ranking weighs five things. Draft quality comes first: does the tool produce a send-ready reply, or just a rough skeleton you rewrite anyway? Voice and tone control matters next — the best tools learn how *you* write or expose tone sliders (formal, friendly, direct) instead of one generic register.

Context awareness is the differentiator in 2027: top tools read the full thread, your calendar, and prior messages so the draft references real specifics rather than boilerplate. Workflow fit covers where the tool lives — a dedicated client, an Outlook/Gmail add-in, a browser extension, or a chat window you copy-paste from. Finally, price and privacy: per-seat cost, free tiers, and whether your email content trains a vendor's models.

We tested against real reply scenarios — scheduling, declines, follow-ups, cold outreach, and apology emails — and favored tools that cut keystrokes without producing the flat, obviously-AI prose recruiters and clients now spot instantly.

1. Superhuman 🏆 BEST OVERALL

Superhuman is a premium email client wrapped around speed and, since the Superhuman AI rollout, genuinely useful writing automation. It connects to Gmail and Outlook accounts and layers keyboard shortcuts, Split Inbox, and Instant Reply on top. Type a short instruction or hit the AI shortcut and it drafts a complete response that mirrors your past writing — it studies your sent mail to match phrasing, sign-offs, and sentence length.

The standout features are auto-summarize, which collapses a 40-message thread into a few bullets, and Auto Draft, which pre-writes replies before you open the message. Ask AI searches your entire inbox conversationally ("what did the vendor quote for Q3?") and pulls the answer.

Pricing runs around $30 per user per month on annual billing, with team plans available. It's not cheap, and there's no free tier, but for someone clearing 100+ emails a day the time recovered justifies it. Best for founders, executives, and account managers who live in email.

2. Microsoft 365 Copilot for Outlook

Microsoft 365 Copilot embeds OpenAI's GPT models directly into Outlook (plus Word, Excel, Teams, and the rest of the suite). Inside an email, Draft with Copilot generates a full message from a one-line prompt, and Coaching reviews a draft you've written for tone, clarity, and reader sentiment before you send.

Its real advantage is grounding in your Microsoft Graph — Copilot can pull from your calendar, recent documents, and Teams chats, so a reply confirming a meeting actually references the correct attendees and file. Summarize condenses long threads at the top of the message, which is a lifeline for anyone returning from PTO.

Copilot is sold as a $30 per user, per month add-on requiring a qualifying Microsoft 365 Business or Enterprise license, usually on annual commitment. That makes it expensive for individuals but a natural choice for organizations already standardized on Microsoft. Best for enterprise and mid-market teams whose entire stack is Microsoft 365.

3. Gemini in Gmail

For Google Workspace users, Gemini in Gmail is the native option. The Help me write feature drafts emails from a prompt, while Refine offers one-tap rewrites — *Formalize*, *Elaborate*, *Shorten* — and Polish cleans up a rough draft. On mobile, Gmail can suggest a complete reply based on the incoming message and your Gmail history.

Gemini also summarizes threads with a chip at the top of long conversations and can answer questions about your inbox through the side panel ("find the contract Maria sent last month"). Because it sits inside the most-used email service on earth, there's zero new app to learn.

Google has bundled Gemini features into Workspace Business and Enterprise plans rather than charging a separate add-on, so most paid Workspace customers already have access. Quality is strong for everyday correspondence, though it can default to slightly verbose, hedge-heavy prose. Best for small businesses and teams already on Google Workspace who want capable AI without buying anything extra.

4. Grammarly

Grammarly evolved from a spell-checker into a full writing assistant, and its generative AI now drafts and rewrites emails anywhere you type — Gmail, Outlook, LinkedIn, Slack, and web forms — via browser extension and desktop apps. Prompt it to "write a polite follow-up" and it produces a draft; highlight your own text and it offers tone adjustments, shortening, and rephrasing.

The signature strength is tone detection: Grammarly flags when your message reads as *unfriendly* or *uncertain* and suggests fixes, which is genuinely useful for high-stakes emails. Its corrections for clarity, conciseness, and correctness remain best-in-class, and it works system-wide rather than inside one app.

Grammarly Free covers basic grammar and limited AI prompts; Grammarly Pro runs around $12 per month billed annually, with Business plans near $15 per user per month adding style guides and brand tones. Best for anyone who writes across many platforms and wants one consistent editing layer over all of it.

5. Shortwave

Shortwave is an AI-native email client built by ex-Google engineers (several from the original Google Inbox team) and runs on top of Gmail. Its AI Assistant can search, summarize, schedule, and write — ask it to "draft a reply declining but offering next week" and it produces a contextual response, then sends after your review.

What sets Shortwave apart is AI-powered organization: it auto-clusters your inbox into bundles, generates thread summaries, and lets you build natural-language AI rules that triage mail without rigid filters. The assistant has real context on your calendar and contacts, so scheduling replies land with correct times and time zones.

Shortwave offers a free tier, with paid Personal and Business plans starting in the $7–$9 per month range and scaling up for teams and heavier AI usage. It's a strong middle ground — more affordable than Superhuman, more email-focused than a general chatbot. Best for Gmail power users wanting an AI inbox without the Superhuman price tag.

6. ChatGPT

ChatGPT from OpenAI isn't an email client, but it remains one of the most capable drafting engines available, and many professionals keep a tab open purely for writing. Paste in a thread or describe the situation and it produces polished emails, adjusts tone on request, and handles tricky genres — bad-news messages, negotiations, multilingual replies — better than most inline tools.

With Custom Instructions and saved Projects, you can store your role, common contacts, and preferred voice so drafts stay consistent across sessions. GPT models handle nuance well, and the Canvas editing mode lets you revise a draft side-by-side instead of regenerating from scratch.

ChatGPT is free at the base tier; Plus is $20 per month, with Team plans around $25–$30 per user per month that keep your data out of training by default. The friction is copy-paste — it doesn't live in your inbox. Best for complex, high-stakes, or creative emails where draft quality outweighs convenience.

7. Claude

Claude from Anthropic is the writing specialist's chatbot of choice. It's widely regarded for natural, less robotic prose — drafts tend to avoid the over-eager filler and obvious AI tells that plague other tools, which is exactly what you want in client-facing email. Paste a messy thread and ask for a concise, warm reply, and the result usually needs little editing.

Claude's large context window lets you drop in entire conversation histories, a brand style guide, and prior emails at once, so it writes with real continuity. Projects store reusable context, and the Artifacts view gives you an editable draft you can iterate on. It's particularly good at matching a specified voice and at the diplomatic phrasing that hard emails demand.

Claude is free to start; Pro is $20 per month, with Team plans for organizations. Like ChatGPT, it lives outside your inbox, so it's a deliberate copy-paste step. Best for writers who care most about tone and natural phrasing.

8. MailMaestro

MailMaestro, built by Maestro Labs (the team behind the former Flowrite), is an AI add-in that lives directly inside Outlook and Gmail. From a few bullet points it generates a complete, professional email, and Improve Draft rewrites your rough text into something cleaner. It supports multiple languages and lets you save templates for repeated message types.

Its useful differentiators are one-click thread summaries inside the message pane and a tone selector that ranges from casual to formal. Because it's an embedded add-in rather than a separate app, drafts appear right in the compose window — no copy-paste, no new inbox to adopt.

MailMaestro offers a free plan with a monthly draft allowance, with paid tiers unlocking unlimited generations, summaries, and team features. It's a targeted, no-fuss option for people who want AI writing without changing email clients. Best for Outlook and Gmail users who want embedded drafting and summaries without leaving their existing inbox.

9. Wordtune

Wordtune, from AI21 Labs, is a rewriting-first assistant that shines when you've already drafted an email and want it sharper. Highlight a sentence and it offers multiple rephrasings plus Casual/Formal, Shorten, and Expand controls — ideal for tightening a clumsy paragraph or softening a blunt one. Its Spices feature can add a counterargument, example, or statistic on command.

Wordtune also generates full drafts and works as a browser extension across Gmail, Outlook web, and most text fields, plus an editor of its own. It leans toward improving *your* writing rather than replacing it, which keeps your voice intact — a meaningful edge over tools that flatten everything into the same register.

There's a usable free tier with limited daily rewrites; paid plans land around $10 per month billed annually for unlimited use. Best for non-native English writers and editors who want to refine their own drafts rather than hand them off entirely.

10. Compose AI 💎 BEST VALUE

Compose AI is a free Chrome extension that adds AI autocomplete and full-email generation to Gmail and text fields across the web. As you type, it suggests the rest of your sentence — accept with Tab — and it claims to cut typing meaningfully for repetitive correspondence. Type a short command like "*//decline the meeting politely*" and it expands into a complete draft.

Its strengths are frictionless autocomplete and custom templates you trigger with shortcuts, which makes it genuinely fast for the routine replies that eat a workday. It also offers rephrasing and tone shifts on selected text. Because it's lightweight and browser-based, setup takes about a minute.

The headline is price: the free plan covers core autocomplete and a monthly generation allowance, with Premium around $10 per month lifting limits. For anyone unwilling to pay for AI email help, this is the most capable no-cost starting point. Best for budget-conscious Gmail users who want speed without a subscription.

FAQ

Which AI email tool writes the most natural-sounding emails? Claude and Superhuman AI tend to produce the least robotic prose. Claude is known for warm, human phrasing, and Superhuman trains on your own sent mail to match your voice. Generic chatbots can sound over-eager unless you prompt them carefully.

Do I have to switch email clients to use AI? No. Grammarly, Wordtune, MailMaestro, and Compose AI work inside your existing Gmail or Outlook, and ChatGPT and Claude require only copy-paste. Only Superhuman and Shortwave replace your client entirely.

What's the best free AI email tool? Compose AI offers free autocomplete and drafting, Grammarly Free covers editing with limited AI prompts, and ChatGPT and Claude both have free tiers. Gemini is included free for paid Google Workspace users.

Will recipients know my email was AI-written? They can if you send raw output. Tools that match your voice — Superhuman, Grammarly's tone controls, Claude — reduce the tells, but always edit drafts for specifics and personality before sending.

Is Microsoft Copilot or Gemini better for email? It depends on your stack. Copilot is stronger if you live in Outlook and Teams; Gemini is the natural fit for Gmail and Google Workspace. Both ground drafts in your calendar and documents.

Which tool is best for non-native English writers? Wordtune and Grammarly lead here because they refine your own drafts and offer tone and clarity controls, preserving your intent while fixing phrasing.

Bottom Line

If email is central to your job, Superhuman delivers the best blend of speed and AI drafting and earns the top spot — provided you'll pay around $30 per user per month. Microsoft shops should default to Copilot for Outlook, and Google Workspace teams already own a capable option in Gemini. For editing across every platform, Grammarly is the safest all-rounder; for the most natural prose on hard emails, keep Claude open. And if you refuse to pay, Compose AI proves you can still get fast, AI-assisted email for free. Trial two or three on your real inbox before committing — the right fit depends far more on where you already work than on any feature checklist.

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Sources

• Superhuman
• Microsoft 365 Copilot
• Google Workspace AI / Gemini
• Grammarly
• Shortwave
• OpenAI ChatGPT
• Anthropic Claude
• MailMaestro by Maestro Labs
• Wordtune by AI21 Labs
• Compose AI

*Best AI tools for email writing in 2027 — compare Superhuman, Microsoft Copilot for Outlook, Gemini in Gmail, Grammarly, Shortwave, ChatGPT, Claude, MailMaestro, Wordtune, and Compose AI for AI email drafting, tone control, and inbox automation.*

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