Best Free AI Email Assistant in 2026: Where Free Runs Out
Free AI email tools use different limits: request quotas, searchable-history windows, geographic eligibility, branded signatures, or DIY setup. We checked current first-party pricing and help documentation on August 10, 2026. Where a vendor does not publish a numeric quota, this comparison says so.
This roundup is organized around the limit rather than the pitch: what stays free, where it ends, and what the next paid tier costs.
What each free tier actually covers
| Tool | Free tier | Where free stops | First paid tier |
|---|---|---|---|
| Carly | Up to 10 Zapier-style workflows with no cap on runs | AI agents are paid | AI agents from $35/mo |
| Gemini in Gmail | Selected summarizing and writing features | Availability varies by feature, region, language, and account | Eligible Google AI or Workspace plan |
| Spark Mail | Full client plus a Basic AI quota | Numeric AI quota is not published; search covers one month | Plus $10/user/mo |
| Shortwave | Basic AI and 90-day search history | Daily quota, 15 threads per search, branded signature | Pro $18/seat/mo |
| MailMaestro | 3 writing requests per week | No free summaries or advanced inbox management | Professional $15/mo |
| Thunderbird + ThunderAI | Free client with third-party AI options | You provide or connect the model and manage setup | Thunderbird stays free |
Carly
Carly is the one where free covers automation rather than drafting, which is why it leads this list.
The $0 plan includes up to 10 Zapier-style workflows with no cap on runs. A workflow can start from an event or a schedule and connect email to other tools. AI agents—the part that reads a message and makes a judgment—start at $35/month. The split is that deterministic plumbing is free and AI judgment is paid.
That matters for email specifically because a large share of inbox work is not writing. It is what happens after a message arrives: a record updating, a file filing, a follow-up scheduling, a person getting notified. Those steps do not need a language model and are exactly what the free tier handles.
Reach is the reason it holds up as the automation layer. Carly connects natively to about 260 apps across more than 45 categories, and can call other public APIs using your own key.
Where free runs out: the moment you want the assistant to make a judgment call. Routing on sender and subject sits in the free tier. “Read this and decide whether it needs my attention” is the paid line, and it is a clean one. If you want to walk through whether that split fits your work before paying anything, you can book a call with the team.
Gemini in Gmail
Gemini’s free Gmail access is fragmented. Personal Gmail users can receive AI conversation summaries in eight supported languages. Help me write is available to personal accounts in the US in those languages, while Suggested Replies are US-only and English-only. Smart features must be enabled, rollouts can vary, and the full Gemini side panel requires an eligible Google AI or Workspace plan or Workspace Experiments.
Where free runs out: there is no single universal line. The free features available to one Gmail account may not appear on another because eligibility differs by feature. The writing tools prepare text for you to review and send; broader side-panel assistance requires a qualifying account.
Spark Mail
Spark’s free tier is a complete multi-account email client and now includes a Basic AI quota. AI Assistant can write, summarize, and answer inbox questions, with free AI search limited to one month of email history.
Where free runs out: Spark does not publish the numeric size of its Basic AI quota, and free users cannot buy quota add-ons after exhausting it. Plus costs $10 per user monthly or $8.25 annually; Pro costs $20 monthly or $16.58 annually.
Shortwave
Shortwave’s free Individual tier gives you basic intelligence with a limited daily AI quota, 90 days of standard and AI search history, and a maximum of 15 threads considered per AI search.
Where free runs out: the 90-day history cap limits questions across older mail, and free accounts append a “Sent with Shortwave” signature to outgoing messages. That signature is a practical drawback for client-facing work. Pro at $18 per seat per month lifts search to three years and removes the signature.
Shortwave only signs in natively with Gmail or Google Workspace. Outlook.com can be forwarded into Gmail, but you cannot send from the Outlook address; Microsoft 365 and Exchange are unsupported.
MailMaestro and Thunderbird
MailMaestro keeps a permanent Free plan after its 14-day trial. It provides three Compose, Reply, or Improve requests per week in Gmail or Outlook. Professional costs $15 monthly or $12 annually and adds summaries, auto labels, reminders, scheduling, and watermark removal.
Thunderbird itself has no first-party AI assistant. Third-party ThunderAI adds analysis, drafting, replies, summaries, tagging, calendar events, and tasks through ChatGPT, Gemini, Claude, APIs, or local Ollama. It can use a free ChatGPT account, but setup, permissions, external-service limits, and support remain your responsibility.
Notion Mail is not ranked because the inbox app shuts down on September 22, 2026. Users must export or migrate drafts, scheduled emails, snippets, and auto-label instructions by September 21. Gmail messages remain in Gmail, and Notion’s Gmail AI Connector and agent email tools continue separately.
Which free tier fits which problem
The choice collapses quickly once you name the actual bottleneck.
If you are slow at writing email, check whether your Gmail account has the relevant Gemini feature. MailMaestro is the clearer provider-neutral allowance: three writing requests each week across Gmail or Outlook.
If you are slow at reading email, Spark and Shortwave both provide limited free AI. Spark supports more mailbox providers; Shortwave is Gmail-only and caps searchable history at 90 days.
If email is generating work in other systems, a free drafting allowance rarely completes the downstream job. Carly’s free automation tier fits deterministic routing and filing steps that do not require AI judgment.
A reasonable free stack depends on your provider and geography: Spark or Shortwave for inbox assistance, MailMaestro for a small weekly writing allowance, and Carly workflows for deterministic downstream actions. Add paid AI when you can name the judgment call you want made for you.
For the paid landscape, our roundup of the best AI email assistants covers what the money buys, and best AI email tools is the wider category view.
FAQ
Is there a completely free AI email assistant?
Yes, but every permanent free option trades something away. Spark and Shortwave provide limited AI allowances; MailMaestro permits three writing requests per week; Gemini’s free Gmail features depend on location and feature; Thunderbird can pair with a third-party add-on and a free or local model. Carly’s non-AI workflows are free, while AI agents start at $35/month.
What is the catch with free AI email tools?
Usually it is a quota, a searchable-history window, a provider or geographic restriction, a branded signature, or DIY setup. Shortwave combines a history limit with a signature; Spark has an unpublished Basic AI quota; Gemini eligibility varies; Thunderbird delegates AI to third-party add-ons.
Can a free AI email assistant send email for me?
It depends on the tool and approval model. Gemini and MailMaestro are review-and-send writing surfaces. Spark exposes sending actions within its free quota, but that is not the same as autonomous delivery. Carly can send from configured workflows, but agent-driven email handling is paid.
Is free enough for a small business?
For light writing or triage, often yes. For client-facing work, watch for signatures and small quotas. For cross-system work such as updating a CRM from an email, compare workflow tools and the exact actions available on their free plans.
What is the best free AI email assistant for Outlook?
Spark offers the broadest free client-plus-AI allowance for Outlook, MailMaestro provides three weekly writing requests, and Thunderbird plus ThunderAI suits DIY users. Shortwave does not support Microsoft 365 or Exchange. Carly’s free workflows support Outlook, while its AI agents are paid. Our best AI assistants for Outlook roundup goes deeper on that side.
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