FMail is a native macOS wrapper for the Fastmail web application, giving Fastmail users a dedicated, standalone desktop experience that behaves like a first-class Mac citizen rather than a forgotten browser tab.
What is FMail?
FMail is an unofficial native Mac application that delivers Fastmail — the privacy-focused email and calendar service — as a proper desktop app, complete with Dock presence, menu-bar integration, and macOS notifications. It isn't a reimplementation of the Fastmail protocol; rather, it packages the Fastmail web interface into a native shell so you get all of Fastmail's own interface polish without sacrificing system-level Mac behaviour.
For Fastmail subscribers who live in macOS, it fills a genuine gap: Fastmail has never shipped its own Mac app, leaving users to choose between a browser tab and third-party IMAP clients like Apple Mail, Mimestream, or Airmail that lose some of Fastmail's custom features (labels, masked emails, custom domains). FMail keeps those features intact because it's running Fastmail's own interface under the hood.
What does FMail do best?
FMail's strongest suit is keeping you in Fastmail's native interface while still feeling like a real Mac app. The moment you launch it, email lands in its own window that you can Command-Tab into, hide, or fullscreen — exactly as you'd expect from any App Store app.
- System notifications: new mail pops up as a native macOS notification, so you can stay out of the window entirely until something arrives.
- Dock badge: unread count stays visible on the icon, which sounds trivial until you've lost a browser tab for the third time.
- Keyboard shortcut to open: assign a global shortcut via macOS and jump to your inbox without touching the mouse.
- Isolated session: FMail keeps its cookies and storage separate from every browser you use, so signing in or out of Fastmail here never disrupts your browsing sessions.
I've been running it as my daily email client for several weeks and the main quality-of-life win is simple: Fastmail's Masked Email, rules, and keyboard shortcuts all work exactly as they do on the web, with no translation layer losing something in transit. IMAP clients like Apple Mail can't say that.
Is FMail free?
FMail is free to download and use. It is an open-source, community-built project maintained independently from Fastmail. You will, of course, still need an active Fastmail subscription to log in — but the app itself costs nothing. Installation is straightforward via Homebrew Cask (brew install --cask fmail) or a direct download from the developer's site.
Who should use FMail?
FMail is squarely aimed at existing Fastmail subscribers who want a tidier desktop workflow. If you're already paying for Fastmail and you find yourself hunting for the right browser tab, this app is a no-brainer install. It's also a natural fit for anyone who uses multiple browsers (work Chrome, personal Safari, dev Firefox) and doesn't want their email session entangled with any of them.
It is not a good fit if you're evaluating Fastmail for the first time — sign up on the web first, confirm the service suits you, then install FMail. Nor does it add anything for users of IMAP-native clients like Mimestream, which has its own polished Mac UI and offline support; FMail is best understood as a thin but effective native shell, not a feature-rich email client built from scratch.
How does FMail compare to using Fastmail in a browser?
The browser experience and FMail's experience are nearly identical in terms of features — because they're running the same code. The differences are purely at the OS integration layer. In a browser, Fastmail competes with every other open tab for your attention and notifications can get lost behind the browser's own notification management. FMail puts Fastmail on equal footing with apps like Slack, Notion, or Linear: its own icon, its own window, its own unread badge. That's the entire value proposition, and for a workflow app you open dozens of times a day, it's not a small thing.
Compared to pairing Fastmail with a full IMAP client, FMail wins on fidelity (every Fastmail feature works) and loses on offline access (no local message cache) and multi-account power features.
What are the best FMail alternatives?
If FMail doesn't fit your needs, the main alternatives for Fastmail users on Mac are: Mimestream (native Mac app, Gmail-architecture client that also works brilliantly with Fastmail IMAP — polished and fast, but costs a subscription); Apple Mail (free, deeply integrated, offline-capable, but loses Fastmail-specific features like Masked Email); and Airmail 5 (multi-account powerhouse, but complex and subscription-priced). For those who want the wrapped-web approach, Fastmail's own Progressive Web App is a browser-native option, though without the Dock presence FMail provides.
