MailTwin
MailTwin vs Shortwave: Gmail-only AI power, or AI for the Mail you have?
Shortwave is one of the most ambitious AI email products on the market — an email client rebuilt around an AI assistant that can search, summarize, draft, and file your mail. It is also, by design, Gmail-only. MailTwin comes from the opposite direction: it's a macOS menubar app that adds AI drafting in your own voice to Apple Mail, working with whatever accounts Mail carries — iCloud, Exchange, IMAP, and yes, Gmail.
So the first question isn't features. It's accounts: if your mail isn't in Gmail or Google Workspace, Shortwave isn't an option without workarounds. If it is, you have a real choice to make — and it comes down to depth of AI automation versus ownership, privacy, and price.
MailTwin’s core workflow: type a few rough reply points and it drafts a complete, editable Apple Mail email in the learned voice for that account. You review every word before insertion; it never auto-sends. Christopher Naas, MailTwin’s maker, says this saves him an hour or more on busy email days — personal experience, not a promised result.
At a glance
| MailTwin | Shortwave | |
|---|---|---|
| What it is | Menubar AI layer for Apple Mail | AI-first email client (web + apps) |
| Accounts | Anything Apple Mail carries: iCloud, Gmail, Exchange, IMAP | Gmail / Google Workspace only (via the Gmail API); other providers only via mail forwarding |
| Price | $19.90 once (5-pack $49.90) | $30–$120 per seat/month by tier (Business/Premier/Max), as of July 2026 |
| Trial | 30 days, full features, no card | 14-day free trial |
| AI engine | Your choice of 8, bring your own key (Claude, OpenAI, Gemini, Groq, Grok, DeepSeek, plus free Apple Intelligence and Ollama) | Claude models in Shortwave's cloud, tiered by plan (Haiku → Sonnet → Opus, as of July 2026) |
| AI limits | None imposed by MailTwin | Daily AI request quotas per tier (e.g. 150–300/day on Business) |
| Voice matching | Learned locally from your sent mail, separately per account | AI drafting informed by your email history (cloud-processed) |
| Mail routing | No MailTwin server ever sees your mail | Mail indexed and processed in Shortwave's cloud |
| Platforms | macOS 13+ only | Web, desktop apps, iOS, Android |
The account question comes first
Shortwave's own documentation is straightforward about this: it supports Gmail and Google Workspace accounts, and users on Outlook, iCloud, Yahoo, or generic IMAP can only participate by forwarding their mail into a Gmail address. If your work runs on Microsoft 365 or your personal mail is iCloud, that's a structural mismatch, not a settings problem.
MailTwin sidesteps the question entirely by building on Apple Mail. Whatever Mail can carry, MailTwin can act on — summaries, action items, translation, and replies drafted in your voice, per account.
Deep automation vs. owned assistance
Where Shortwave shines is agentic depth. Its assistant can execute multi-step tasks across your inbox, its AI filters triage mail automatically, and higher tiers run stronger Claude models with adaptive reasoning (as of July 2026, Shortwave's tiers map to Claude Haiku, Sonnet, and Opus models). If you want an AI that actively manages a high-volume Gmail inbox, Shortwave is arguably the deepest tool available.
MailTwin is deliberately narrower and more conservative: it drafts, summarizes, translates, and improves — always visibly, never autonomously. Its Inbox Cleanup produces a reviewable plan with receipts and undo rather than acting silently; follow-up checks run only when you click "Check for replies," and they read metadata only. Every rewrite passes an on-Mac validator that rejects changed numbers, dates, links, or invented sign-offs. Nothing sends, files, or changes without you.
Interestingly, both products can run on Claude — the difference is who holds the account. Shortwave includes Claude in its subscription with daily quotas. MailTwin lets you bring your own Claude key (or seven other engines, two of them free and on-device) with no quotas beyond what your provider bills.
What it costs
Shortwave's paid tiers run $30 (Business), $45 (Premier), and $120 (Max) per seat per month as of July 2026, with AI allowances rising by tier. Its pricing page lists no permanent free tier for new signups — the 14-day trial is the entry point.
MailTwin is $19.90 once — less than a single month of Shortwave's entry tier — with a 30-day full trial and lifetime 1.x updates. AI costs are whatever your chosen provider bills (or nothing, on-device), with a live cost log in Settings.
Where your mail lives
Shortwave's model requires your mail to be indexed and processed in its cloud — that's what makes its AI search and agents possible, and the company documents its practices. It's a fair trade for the capability, but it is a trade.
MailTwin has no server in the mail path at all. Voice learning happens locally from sent mail you explicitly index; AI calls go directly from your Mac to your chosen provider, or stay on-device with Apple Intelligence or Ollama. Telemetry is opt-in only, pseudonymous, and deleted within 90 days.
Choose Shortwave if…
- You live in Gmail or Google Workspace and want the deepest AI automation available for it — agentic task execution, AI filters, and AI-native search are genuinely ahead of anything in Apple Mail.
- You want your assistant on the web and mobile too. MailTwin is macOS-only with no mobile app.
- You manage very high volume and want AI triaging mail before you see it.
- Team features matter, and per-seat SaaS pricing fits how you buy software.
Choose MailTwin if…
- Your accounts live in Apple Mail — iCloud, Exchange, IMAP, or Gmail-in-Mail — and Shortwave's Gmail-only design rules it out.
- You want AI that drafts in your voice, kept separate per account, learned locally and only when you ask.
- You prefer explicit, reviewable actions with undo over autonomous inbox management.
- You'd rather pay $19.90 once than $360+ per year. The honest trade: MailTwin is Apple Mail-only, macOS-only, has no mobile app or team features, expects you to manage an API key for cloud engines (two engines need none), and is a v1 product.
FAQ
Does Shortwave work with Outlook or iCloud email?
Not directly. Shortwave supports Gmail and Google Workspace only; its own docs describe forwarding mail into a Gmail address as the workaround for other providers.
Does MailTwin work with Gmail?
Yes — through Apple Mail. Add your Gmail account to Mail as usual, and MailTwin's actions work on it like any other account, including a separate learned voice for it.
Which is cheaper, MailTwin or Shortwave?
MailTwin is $19.90 one-time. Shortwave starts at $30 per seat per month as of July 2026 — so a single month of Shortwave costs more than MailTwin does forever.
Do both use Claude?
They can. Shortwave runs Claude models in its cloud with per-tier quotas. MailTwin lets you bring your own Claude key — or choose OpenAI, Gemini, Groq, Grok, DeepSeek, or free on-device Apple Intelligence/Ollama.
Is MailTwin's AI autonomous like Shortwave's?
No, deliberately. MailTwin acts only when you ask, shows you a reviewable plan for cleanup actions with receipts and undo, and validates every rewrite on your Mac before it touches a draft.
Try it on your own mail
If your mail lives in Apple Mail, the comparison takes five minutes to run yourself. 30-day full trial, no card, then $19.90 once.