Postbox Alternatives After It Was Discontinued

Postbox is discontinued. eM Client — the desktop email client for Windows and macOS — acquired Postbox, Inc. and announced on 22 October 2024 that Postbox "will no longer be sold or developed." Support ran through 22 December 2024, and the Postbox help center itself was scheduled to go offline on 22 December 2025, a date that has already passed as of this writing. If you're still running an old Postbox build, nothing stops it from launching today, but there will be no more security patches, no bug fixes, and no support if a future macOS or Windows update breaks something.

The fastest official migration path is eM Client, built for exactly this transition: it auto-detects an existing Postbox install and imports mail, accounts, and rules for you. Thunderbird is the free option, and it shares Postbox's original Mozilla codebase, so reconnecting accounts feels closer to home than a total rebuild. If what you actually want is an AI layer on top of whatever client holds your mail — automatic triage, drafted replies, one searchable view across every account — that's AI Emaily, our own product, and it's covered first below because it solves a different problem than the other seven: not where your mail lives, but what happens to it once it arrives.

We build AI Emaily. Below is the full field in order: what each option actually replaces, how a Postbox migration goes for each, and — honestly — where each one falls short, including ours. Every dated claim here is checked against a vendor's own page, not a news summary or a forum thread.

How we compared#

We compared eight replacement options on what actually decides whether a Postbox migration goes smoothly: does the tool import your existing mail without a manual re-download, does it run on the platforms you actually use, and does it solve the job you used Postbox for — a fast, configurable desktop client, or something that also acts on the mail once it lands.

Every packaging note below describes shape only — free tier, trial, per-seat, or usage-metered — never a specific price. Vendor pricing pages change on their own schedule, and we'd rather point you to the live number than publish one that goes stale the week after this page ships. The same caution applies to features: where a vendor doesn't publish a Postbox importer, that's stated as "not published," not as a claim that the feature is absent.

Every dated claim on this page — the Postbox shutdown timeline especially — is checked against the vendor's own announcement rather than press coverage, and stated as of July 2026. If you're reading this later, re-check the primary source before you act on a date.

Postbox alternatives compared#

The table below is the shortlist. "Postbox migration path" means what actually happens to your mail and settings when you switch — an automatic import, a manual IMAP reconnect, or something in between.

Why we ranked AI Emaily first#

We're not neutral here — this is our site, and AI Emaily is the product we sell — so the criteria are worth stating plainly instead of pretending the list is unranked. We put weight on approve-before-send drafting, an undo and audit trail on every automated action, and coverage across Gmail, Outlook, and IMAP without a migration step, because those are the things we built AI Emaily around, and they're also what a Postbox refugee tends to care about most: control over what a tool does with their mail, and account coverage rather than a single provider.

Most of the field below doesn't compete on those dimensions at all, and that's a fair thing for them not to do — eM Client and Thunderbird are mail clients, built to store and display mail well, not AI agents built to act on it. The honest comparison isn't "AI Emaily beats a Mozilla-based mail client at rendering email"; it doesn't try to, and a page that claimed otherwise wouldn't be worth reading.

What's true is narrower and more useful: if what you want after Postbox is a tool that also acts on your mail — files it, drafts replies, keeps one brief across every account — none of the other seven options here are built for that job. If what you want is simply somewhere for Postbox's mail to land, eM Client or Thunderbird will serve you better, and we say so throughout this page rather than only in the fine print.

1. AI Emaily#

AI Emaily is the tool we build, and it sits in a different category than the rest of this list: it isn't a client-side mail store the way Postbox was, so there's no local profile to import. You connect Gmail, Outlook, iCloud, Yahoo, Fastmail, Zoho, GMX, or any IMAP account directly, and AI Emaily works from those accounts rather than a file on disk.

Once connected, it triages incoming mail, drafts replies from a Personal Context brain you set yourself — not an automated read of your sent history — and gives you one searchable inbox across every account instead of a separate window per provider. If you liked Postbox for the control it gave you over what happened to a message, two things carry over directly: Copilot mode holds every AI-drafted send for your approval before it goes, and every automated action — filed, labeled, drafted — is logged with an undo, so nothing acts on your mail invisibly.

The honest limit: AI Emaily ships as a real downloadable desktop app — macOS (Apple Silicon only, no Intel build) and Windows — plus a native iOS app, a browser PWA on Android, and the web, but the desktop app is an Electron shell over the web codebase, not a native Swift or Win32 client. It won't match a native binary on raw memory footprint, and offline mode covers reading and drafting, not a complete local archive the way Postbox's own engine did.

Packaging shape: free tier plus paid plans, per-seat for teams. Check current tiers on our pricing page before committing.

2. eM Client#

eM Client is the company that acquired Postbox, and its migration path is built to match: the app auto-detects an existing Postbox install during first-run setup and lets you choose which accounts, mail, and rules to bring over — verified directly on eM Client's own Postbox migration page. That auto-detection makes it the only option on this list actually engineered for this specific transition, rather than a generic IMAP reconnect dressed up as one.

It runs on Windows and macOS, and bundles calendar, contacts, tasks, and notes alongside mail — a broader personal-information manager than Postbox ever tried to be, which is either a bonus or clutter depending on what Postbox was doing for you. eM Client's published migration guidance doesn't explicitly cover calendar data as part of the standard import, so check that specifically if Postbox held your calendar too.

Packaging shape: a free tier capped to a limited number of accounts, plus a paid Pro license. eM Client has also run a discounted license offer specifically for migrating Postbox users — confirm the current offer on its own site rather than assume the original one is still live.

3. Thunderbird#

Thunderbird is free, open-source, and shares something real with Postbox: Postbox was originally forked from Thunderbird's own Mozilla codebase back in 2008, by former Thunderbird engineers who wanted a different product direction. That shared lineage means the underlying mail-handling is close enough that reconnecting your accounts over IMAP feels familiar rather than like starting from zero, even though Thunderbird doesn't publish a one-click Postbox importer.

It runs on Windows, macOS, and Linux — the only cross-platform option on this list besides AI Emaily's web app — and it's funded by donations rather than a subscription, so there's no tier to pick. Add-ons cover calendar and end-to-end encryption if you need them.

What you lose moving from Postbox is the polish: Thunderbird's interface is more utilitarian, and specific Postbox features like the Compose sidebar and image gallery don't have a direct equivalent. What you gain is a mail client that will still exist in five years regardless of any company's acquisition.

4. Mailbird#

Mailbird is a Windows-only client built around a single unified inbox and a more visual, app-like layout than Postbox's dense, power-user interface. It doesn't publish a dedicated Postbox importer, so migrating means reconnecting each account by IMAP or provider login and rebuilding filters from scratch — a real cost if you had years of Postbox rules and Smart Folders tuned.

Where it earns a look: native integrations with apps like WhatsApp, Asana, and Trello inside the inbox itself, aimed at people who want fewer open tabs rather than more automation. It's Windows-only, so it isn't an option at all if any part of your setup touches Mac or Linux.

Packaging shape: a free trial period followed by paid tiers, with per-seat pricing for team accounts. Check the current trial length and tier lineup on Mailbird's own site directly — it has revised its packaging before.

5. Canary Mail#

Canary Mail is Mac- and iOS-only, built around on-device AI features — summarization, smart replies, a priority inbox — alongside built-in PGP encryption, which puts it closer to a privacy-focused Postbox successor than most of the field. Like Mailbird, it doesn't publish a dedicated Postbox importer; migrating means reconnecting accounts and rebuilding rules by hand.

If Postbox appealed to you for its encryption add-ons or its Mac-native feel, Canary is arguably the closest match on this list on both counts, though the two aren't built on shared code and won't behave identically account for account.

The limit: no Windows or web version, so it isn't usable if any part of your workflow needs cross-platform access. Packaging shape: a free tier covering core mail, with a paid subscription unlocking the AI features and some encryption options.

6. Spark#

Spark, from Readdle, is built for shared inboxes and team collaboration — comments on threads, shared drafts, AI-assisted writing — which makes it a better fit for a small team than for the solo power-user workflow Postbox mostly served. It runs on macOS, Windows, iOS, and Android, giving it the broadest platform coverage on this list after AI Emaily and Thunderbird.

There's no dedicated Postbox importer, so migration follows the same manual IMAP reconnection as most of this list. Spark's AI drafting works from the specific thread it's replying to rather than from a personal writing profile you configure once — a different mechanism than the templates Postbox users tend to have built by hand over years.

Packaging shape: a free tier for individual use, with a paid subscription for collaboration and AI features, priced per seat for teams.

7. MailMate#

MailMate is a Mac-only IMAP client built for the same audience Postbox served — people who want deep tagging, saved searches, and scriptable automation instead of a simplified inbox. If Postbox's power-user features are what you'll miss most — Smart Folders, dense keyboard control, multi-account tag search — MailMate is the closest philosophical match on this list, even though it's a separate codebase with its own learning curve.

There's no Postbox importer; migration means reconnecting accounts over IMAP and rebuilding your tag and search setup by hand, which will take longer than any other option here, in exchange for landing on a tool built for the same kind of user Postbox was.

Packaging shape: a paid license with a trial period. Unlike Thunderbird's donation model or the free tiers elsewhere on this list, MailMate has no permanent free tier — check the current trial length on the vendor's site.

8. Apple Mail#

Apple Mail is free, built into every Mac, iPhone, and iPad, and needs no migration tool at all — you reconnect your accounts through System Settings or Mail's own account picker, and there's nothing separate to install because there's no import, just a login.

It's the right call if what you actually want after Postbox is the simplest possible mail app and you're already fully inside the Apple ecosystem. It's the wrong call if you relied on Postbox's advanced search, Smart Folders, templates, or the range of third-party account types Apple Mail supports less thoroughly, since Apple Mail's own rules and search stay fairly basic by comparison.

Packaging shape: free, bundled with macOS and iOS. There's no paid tier because there's no separate purchase to make.

How to choose for your situation#

Match the choice to what you actually used Postbox for, not to which option ranks highest on a review page. Each situation below points to a different answer, and more than one can apply at once.

• Want the least effort, closest to "Postbox but maintained": eM Client. It's the only option on this list built specifically for this migration, with automatic Postbox detection on first run.
• Want free forever with no acquisition risk hanging over it: Thunderbird. Same Mozilla lineage as Postbox, cross-platform, no subscription to track or lose.
• Want your inbox actively triaged, not just displayed — replies drafted, low-priority mail filed automatically, one view across every account you own: that's the job AI Emaily does, and it's worth layering on top of whichever client above ends up holding your raw mail. We build it, and it's the only option on this list actually built for that job rather than for local mail storage.
• Were a Postbox power user specifically for its tagging, Smart Folders, and scriptability: MailMate is the nearest philosophical match, at the cost of a manual rebuild.
• Need a shared inbox with comments and collaborative drafts for a small team: Spark.
• Are already all-in on Apple hardware and want zero setup: Apple Mail.