Use built-in help before adding an extension
Gmail users already have Smart Compose and Smart Reply, which handle predictive text and short responses with no extension or credits. Beyond that, each tool asks for more access in exchange for more help. Compose AI drafts inside Gmail or Outlook, ChatGPT’s free tier writes longer messages from whatever you paste into it, and Boomerang for Gmail adds a basic response-likelihood meter. Spike only makes sense if you also want to replace the email app itself. Teams that need custom-domain mail should begin with our free team email guide before adding an AI layer.
Inbox access raises the privacy cost
Business email time adds up across drafting, changing tone for a client or colleague, summarizing a long thread, and fixing a half-formed sentence before sending. The tools below address those tasks, but their quotas and data access differ.
Free tools now cover predictive compose, assisted replies, tone feedback, and subject-line ideas. Limits, credits, and inbox access vary by provider, so compare the feature inside the account and mail workflow where it will be used.
Where the draft is created, what context the tool can read, and whether sensitive business text may leave the mail provider matter more than the size of the free allowance.
Five ways to add AI help to email
1. Gmail Smart Compose and Smart Reply: best built-in free AI for most people
Smart Compose predicts the rest of your sentence as you type. Smart Reply generates three short response options at the top of any email you open.
Gmail’s built-in features are free because they are part of Gmail itself:
- Smart Compose in compose and reply windows across all Gmail accounts
- Smart Reply suggestions on incoming emails
- Personalization over time: the model adapts to your phrasing and common contacts
- Works in Gmail web, Android, and iOS
- No usage caps or credit limits
The limit is that Gmail helps with small pieces, not full email workflows:
- Smart Compose writes completions, not full drafts: you still need to initiate and structure the email yourself
- Smart Reply only works for short responses; longer threads require composing from scratch
- No thread summarization on Gmail Free; Gemini in Gmail comes with a paid Google AI or Google Workspace plan
- No AI subject line generation or tone adjustment
It covers quicker replies, sentence completions, and light phrasing help, not thread summaries or a sensitive client reply written from scratch. Because it requires nothing beyond your Gmail account, there is no extension to approve, no new app to trust with inbox access, and no credit balance to monitor. That makes it the safest default for basic email assistance.
2. Compose AI: best free extension for full AI-drafted email
Compose AI works inside the compose box rather than beside it. The Chrome and Edge extension adds writing features to Gmail, Outlook, and most web-based text inputs, and you can ask it to write a full email from a prompt, rephrase a selection, adjust the tone, or continue from where you left off.
Compose AI’s free Basic plan is useful when you want drafting inside the compose box:
- 50 advanced autocompletes a month
- 1,500 words of generated text a month from a short prompt
- 25 rephrase, shorten, or expand actions a month
- 10 one-click email replies a month
- Works inside Gmail, Outlook, LinkedIn, and other web text fields
The main thing to watch is the monthly allowance:
- Those allowances, listed on the pricing page, cover light use rather than a full day of email
- No email thread summarization
- No calendar or CRM integration
- The extension adds a visible toolbar overlay that takes up space in the compose window
Writing inside the compose window, rather than generating in ChatGPT and pasting the text across, removes an extra step from every draft. That suits professionals who spend the day in Gmail or Outlook, as long as the current allowance covers their daily volume.
3. ChatGPT free tier: longer drafts with manual context
ChatGPT drafts and revises messages from instructions supplied in a separate chat, which covers flexible drafting:
- Access to the models and tools currently included on the Free plan
- Drafts, rewrites, tone adjustment, subject line options, follow-up emails, and cold outreach templates
- Web and mobile access, with model and tool availability that can change
- Works for any email type: professional, sales, customer service, personal
The copy-paste workflow keeps inbox connections optional:
- You copy email context into the chat and paste the finished draft back
- With no inbox connected, email history and threads must be supplied manually
- Some models, reasoning modes, uploads, and other tools have separate limits
That separation suits longer drafts where you want to control exactly what context leaves the inbox. Do not paste confidential, regulated, or employer-restricted information into a consumer AI account.
Leaving the inbox unconnected adds a manual checkpoint: you decide what to paste and can remove identifying details first. ChatGPT also supports authorized email connections, with availability depending on the plan, region, account, and workspace. OpenAI’s Free Tier FAQ says available models and limits can change, so the in-product notice is the reliable source for a specific account.
4. Boomerang for Gmail: best free AI email quality scorer
Boomerang scores a message instead of writing it. The Gmail extension adds scheduling, follow-up reminders, and a quality checker called Respondable. Before you send, its meter estimates response likelihood from basic writing factors.
Boomerang’s free tier covers:
- 10 message credits per month for Boomerang scheduling and follow-up features
- Respondable AI writing assistant active on every email you compose (not subject to the 10-credit cap)
- Basic Respondable feedback on every email you compose
- No credit card required
The free tier is narrow:
- Scheduling and boomerang features are limited to 10 credits per month, which resets monthly
- Positivity, politeness, and subjectivity scores require a Pro or Premium plan
- No mobile app
- Respondable scoring is advisory: it does not rewrite or suggest alternative phrasing, only scores
It fits people who send high-stakes requests, sales emails, introductions, or follow-ups where response quality matters. The tool is less useful if you want the AI to write the message for you.
Respondable’s basic meter is not charged against the ten monthly scheduling credits. Boomerang’s Respondable FAQ identifies positivity, politeness, and subjectivity as advanced paid measurements.
5. Spike: best free dedicated AI email app
Spike replaces the email client itself, on web, desktop, iOS, and Android, with a chat-like interface and a built-in writing assistant that drafts replies, summarizes threads, and adjusts tone.
Spike combines an email client and AI tools in one app:
- 10 free queries each for AI message generation, conversation summaries, and the AI assistant
- One email address on the free plan
- Smart inbox and chat-style email interface
- Limited search history and storage on the free plan
- Works with Gmail, Outlook, Yahoo, and IMAP accounts
Spike only makes sense here if changing email clients is acceptable:
- Unlimited AI use, multiple email addresses, longer search history, and higher storage require paid plans
- Spike replaces your existing email client rather than adding to it: users who prefer Gmail or Outlook’s native interface will find the switch disruptive
- Team features such as shared inboxes and heavier collaboration require paid plans
It suits individual professionals willing to change their primary inbox in exchange for built-in drafting, thread summaries, and a conversation-style view. Its pricing table lists the current ten-query allowances and one-address limit.
Compare inbox access and free usage
| Tool | AI drafting | Summarization | Integration | Free tier limit |
|---|---|---|---|---|
| Gmail Smart Compose | Predictive only | No | Gmail native | No cap |
| Compose AI | Yes: full drafts | No | Gmail + Outlook extension | Monthly credits |
| ChatGPT free | Yes: full drafts | Yes (paste thread) | Manual copy/paste here; connections vary by account | Limits vary by model and tool |
| Boomerang | No (scoring only) | No | Gmail extension | Scheduler: 10/month |
| Spike | Yes | Yes | Standalone app | 10 AI queries per feature + 1 address |
Privacy and business-use considerations
AI email tools that connect to your inbox via OAuth, including Compose AI, Boomerang, and Spike, request permission to read and manage your email. Before connecting any third-party tool to a work account, check:
- What data the tool sends to its servers. Compose AI and Spike both process message content to generate AI outputs. Review each provider’s privacy policy and data processing agreement before connecting a business inbox.
- Whether your employer’s IT or security policy permits third-party email integrations. Many organizations restrict OAuth access to prevent data leakage.
- GDPR implications for European businesses. Tools that process EU personal data through US-based AI infrastructure require reviewing data transfer mechanisms and DPA agreements.
Boomerang says basic Respondable analysis runs in the browser, while its advanced machine-learning measurements send message data to its servers. Compose AI and Spike process content to generate drafts or summaries. For confidential client information, legal correspondence, or financial data, follow the account owner’s security policy and only share content that is approved for that service.
When the free tier runs out
The free options cover different levels of use. An upgrade may become relevant when:
- Credits or tool limits interrupt the normal workflow.
- Several people need shared features or administration.
- Direct CRM or calendar automation becomes a requirement.
- The organization requires contractual data-processing or governance controls that a consumer free tier does not provide.
For teams that have outgrown individual free tools, the paid tiers of Compose AI, Spike, or a full email client with Copilot integration are the natural next step. What each paid step costs, from the US pricing pages in September 2026:
| Tool | Paid step | Price | Adds for email |
|---|---|---|---|
| Gmail | Google AI Plus, or Workspace Business Starter | $4.99 a month, or $7 per user a month | Gemini in Gmail for drafting and thread summaries; AI Plus also includes 400 GB of storage |
| Compose AI | Premium | $9.99 a month billed yearly | 25,000 generated words a month, unlimited rephrasing and autocomplete, 50 one-click replies |
| ChatGPT | Plus | $20 a month | Higher limits and authorized email connections where available |
| Boomerang | Personal | $4.98 a month billed yearly | Unlimited scheduling credits; Pro, at $14.98, adds Respondable’s advanced scores |
| Spike | Pro | $6 per user a month billed yearly, $8 monthly | Up to three email addresses, unlimited search history, 5 GB of storage |
| Outlook | Microsoft 365 Personal | $9.99 a month or $99.99 a year | Copilot inside Outlook and the other Office apps |
The Gmail and Outlook upgrades keep drafting inside the provider you already trust with the mail, which avoids granting a third-party extension inbox access.
Start outside the inbox, then add access deliberately
Add access one step at a time, and only when the step before it runs out. Built-in Gmail Smart Compose reads nothing new. A manual ChatGPT chat lets you choose which email text to share. Connecting ChatGPT or an extension such as Compose AI or Boomerang asks for inbox permissions. On a work account, that step needs the account owner’s approval before it needs a free trial.
Pair these tools with a provider from the free email service guide and a reusable HTML email signature. For writing beyond email, the free AI writing tools guide compares drafting and revision tools.



