Best Cross-Platform Email Client for Mac and Windows

You use a Mac at home and a Windows PC at work — or the other way round — and you want one email client on both. That is easy. Almost every serious desktop client now ships on both platforms. The hard question is the second one: which of them keep your settings, rules, snoozes, drafts and signatures in sync across the two machines, so you set things up once instead of twice?

That is what this roundup answers. Not "the best cross-platform email client for Mac and Windows" by feature count — every review site has that list — but by state parity. Which apps let you make a rule on the Mac at 8pm and have it fire on the PC at 9am. Which do not. Which force you to reconfigure everything the moment you sit at the other keyboard. That is the difference that matters when you actually live on both.

We ship AI Emaily, so you are on the vendor's site — we say up front where we lead and where we do not, and we name the two clients that are stronger than us on specific dimensions. The full disclosure sits in the AI Emaily section below.

The short answer#

If you want AI triage, drafting, and rules that follow you between desktops, our pick is AI Emaily — first because we built it around a server-side agent and shared account state, so the same rules, Context brain, drafts, snoozes and autonomy settings appear on both installs the moment you sign in. We build AI Emaily; the desktop apps are Electron shells wrapped around the web app, which is the mechanism that makes state parity easy.

If you want a calm, feature-rich desktop client with cross-device settings sync and no AI agent, eM Client is the honest pick. If you live entirely inside Gmail and want the strongest keyboard-driven AI workflow on both desktops, Shortwave is the better fit than we are on that specific axis. If you want $0 forever, open source, and are willing to keep filters in sync yourself, Thunderbird is genuinely the right answer — and no one else on this page can honestly claim any of those three things.

How we compared: state parity, not just OS coverage#

Almost every review of "cross-platform email clients" collapses into a features table where the two OS logos sit next to a green tick and no one asks the follow-up question. The follow-up question is: is it one client, or two clients that happen to share a name? Because the difference decides whether "cross-platform" means anything to you.

A truly cross-platform client stores its state — accounts, rules, snoozes, drafts, signatures, saved searches, keyboard remaps, sometimes even column widths — in a server-side account you sign into on both machines. Change something on the Mac, sign in on the PC, and it is already there. A pseudo-cross-platform client just ships a binary for both OSes and stores state locally in each install, so a filter you created on Windows never fires on the Mac until you copy a config file over by hand.

The dimensions we scored, in the order we care about them:

• State sync across installs — do rules, snoozes, drafts, signatures and saved views appear on the other machine automatically, or do you rebuild them?
• Mail-account coverage — Gmail, Outlook/Microsoft 365, iCloud, IMAP, and Exchange EWS. Some clients only handle one provider well.
• Native versus Electron shell — a native-toolkit binary is lighter and integrates deeper with the OS; an Electron shell ships features on both platforms faster and identically. Both are legitimate; the honest thing is to name which is which.
• AI capability where it exists — triage, drafting in your voice, semantic search, and whether AI settings themselves sync between installs.
• Approval model — for anything AI writes or sends, is there a human-in-the-loop step, an undo, and an audit log? This matters more once the agent is doing more.
• Packaging shape — free tier, free trial, per-seat, one-time license — and whether the license itself covers both OSes.

Cross-platform email clients at a glance#

The table below is scored on the dimensions above. "State sync across installs" is the column most other roundups skip; it is the one that actually decides whether your second machine feels like the same client or a second setup job.

AI Emaily: our pick if you want AI triage with cross-device state#

AI Emaily is an AI-native email client that connects to Gmail, Microsoft 365, iCloud, Fastmail, Proton, Yahoo and any IMAP mailbox. On desktop it ships as a downloadable Mac app (Apple Silicon only — there is no Intel Mac build, and it is not on the Mac App Store) and a downloadable Windows installer. Both are Electron shells around the web app, and that is the mechanism that makes cross-device state trivial: your rules, Context brain profiles, drafts, snoozes, signatures, saved searches and autonomy settings live in your account, not in the local install. Sign in on the other machine and they are already there.

The reason to pick us specifically for a Mac + Windows workflow is the agent, not the shell. AI Emaily has a chief-of-staff mode with three levels of authority — Manual (you send everything), Copilot (it drafts, you approve with one tap), and Autopilot (it acts within rules you set, with undo and a full audit log). Because those authority settings sync too, the shift you built on Monday's Mac keeps running on Tuesday's PC without a second setup. The voice framing matters honestly here: we do not "learn your tone from your sent mail." You set a Personal Context brain and per-client profiles, so the voice is one you deliberately shape, not one guessed from history you cannot see.

Where we are not the right pick, plainly: if you need a native-toolkit binary that matches Apple Mail or Mimestream on memory footprint and deep OS integration, an Electron shell will not. If you must run Linux on the desktop, we do not ship a Linux build. If you need an Intel Mac build, we do not have one. And if you cannot pay anything, we are not the option — there is no public free plan, only a 7-day free trial on Pro or Autopilot (card taken, $0 charged if you cancel before day 7). Details and current numbers on the AI Emaily pricing page. We build AI Emaily.

eM Client: the calm, feature-rich cross-platform option without an AI agent#

eM Client is the pick if you want a mature desktop client that feels native on each OS, ships on both Mac and Windows, and keeps your rules, categories, templates and text snippets in sync between the two through an eM Client account. It handles Gmail, Microsoft 365 (including Exchange), iCloud and any IMAP mailbox, and its calendar and contacts integration is one of the reasons long-time Outlook refugees pick it.

There is an optional AI add-on for drafting and summarizing, but the appeal for most people is the opposite: a calm, dense, keyboard-driven client that does the classic things well without a chatbot in the middle. Packaging shape is a free tier for personal use with limits on the number of accounts, plus paid Personal and Business tiers — check the vendor's live pricing page for the current numbers, because personal versus business inclusion has moved around.

Where eM Client is not the right pick: if you specifically want an AI-native workflow with an approval model and an audit log around agent actions, the add-on style is not built for that shape, and this is where we would honestly point you back to a purpose-built AI client. Where it wins outright over us: if you want a dense, calm classic client that already has ten years of polish, and the AI question is either "not now" or "no thanks," eM Client is stronger than we are on that fit.

Spark Mail: the widest device coverage that keeps state in sync#

Spark from Readdle ships on Mac, Windows, iOS, iPadOS, Android and Apple Watch. If your "cross-platform" question is really "I want the same client on every device I own," nothing on this list matches Spark's spread. Accounts, snoozes, templates, signatures and read status sync through a Readdle account, and the mobile apps are genuinely good rather than an afterthought — a Spark strength for years.

Spark added AI drafting and summarize under its Spark+ subscription, and there is a team-plan variant with shared drafts. For a mixed Mac + Windows + phone household, the story is straightforward: one client, one account, snoozes and drafts already there when you switch device.

Where Spark is not the right pick: if you want an agent that acts on the inbox with rules, undo and an audit log, Spark's AI is drafting and summarizing rather than triage-and-act. If you want no cloud middle-layer at all, the Readdle account is not optional. Packaging is a free tier plus Spark+; check the current pricing page.

Shortwave: the Gmail specialist that ships on both desktops#

Shortwave is a Gmail-only client built by ex-Google engineers, shipping as an Electron desktop app on Mac and Windows plus mobile. Because it is Gmail-only, cross-install state sync is easy by construction — labels, searches, and read state already live on Google's servers. Shortwave adds a strong AI layer on top: chat with your inbox, summarize threads, and a well-regarded semantic search that surfaces messages by meaning rather than exact keyword.

This is where we owe a straight concession. Shortwave has built harder on Gmail-specific semantic search and thread-chat than we have, and if you live entirely inside Gmail and want the fastest keyboard-driven AI workflow on both desktops, Shortwave is a better fit than AI Emaily on that specific axis. We handle Gmail well, but we spread across Gmail, Outlook, iCloud, Fastmail, Proton and IMAP; a specialist that only has to be brilliant at one provider gets to go deeper on that provider's quirks.

Where Shortwave is not the right pick: any inbox that is not Gmail. No Outlook, no IMAP, no iCloud. If your Windows PC is really a Microsoft 365 work account, this is a hard stop. Packaging shape is a free tier plus paid tiers with a card-taken trial on paid — check their live pricing page for current numbers.

Thunderbird: the honest pick if you want free forever and don't need sync#

Thunderbird is the client that runs on Mac, Windows and Linux (the only one on this list that ships all three), is completely free and open source, is funded by donations, and does not require you to sign into any vendor account to use it. If those four sentences describe what you want, no one else on this page can honestly match all four.

The second concession this post owes is here. If you specifically want $0 forever, no telemetry story to worry about, and full local control over your mail — with the trade-off that you handle the cross-machine sync question yourself — Thunderbird is genuinely the right answer, not us. AI Emaily is a paid product and does not compete with "free forever."

The honest limit is the one the whole post turns on: Thunderbird does not sync filters or settings between installs. Its profile and its msgFilterRules.dat file are per-install. Users on the Mozilla community forums have been asking for cross-machine sync for years, and it is on the wishlist rather than in the product. Workarounds include copying the profile folder, symlinking the filter file, or moving your filters server-side to Gmail or your host. If you can live with that manual step, Thunderbird is unbeatable on price and openness. If you cannot, one of the others on this list is a better spend of your setup time.

BlueMail: the option with a Linux desktop and MagicSync#

BlueMail ships on Mac, Windows, Linux, iOS and Android, and its MagicSync feature links your devices so accounts and settings follow you across them. That combination — full Linux desktop plus real cross-device settings sync — is unusual enough that it is worth mentioning even in a Mac-and-Windows roundup, because plenty of readers of this article also have a Linux box in the workflow.

BlueMail has added BlueAI for drafting and summarizing, sitting alongside the calendar, unified inbox and cluster views the client is known for. Packaging is a free tier plus a Pro subscription — the vendor's page has the current numbers.

Where BlueMail is not the right pick: the UI is denser and busier than Spark or Shortwave, and the AI is drafting-and-summarize rather than agent-with-approval. If you want a minimalist look or a full autonomy model, this is not the fit.

Mailbird: the Windows-first client that finally added Mac#

Mailbird was a Windows-only desktop client from 2013 until October 2024, when it added macOS. A single Mailbird account now covers Pro features on both installs, so if you buy it, you install it on the Mac and the PC and Pro is live on both without a second purchase. It supports Gmail, Microsoft 365, iCloud and IMAP, with a large set of add-in integrations (chat apps, calendars, task managers) that has been the product's calling card for years.

Packaging shape is a free trial and a paid subscription, with a lifetime option — check the vendor page for the current tiers, because Mailbird has moved its pricing packaging several times.

Where Mailbird is not the right pick: the Mac build is relatively new, so if you want a client that has been Mac-first-and-mature for a decade, Apple Mail or Mimestream (Gmail-only, Mac-only) are the honest fits, not this list. And it is add-in-and-integration led, not AI-agent led.

Superhuman Mail: fast, paid, and now part of the disambiguated Superhuman brand#

Superhuman Mail is the fast, keyboard-driven Gmail and Microsoft 365 client that has been paid-only for years and ships as an Electron app on Mac and Windows plus mobile. Because it is account-driven, the same inbox view appears on both installs when you sign in. AI features have moved from add-on to first-class — triage, drafting, and per-conversation instructions.

The disambiguation matters in 2026: Grammarly acquired the Superhuman email client in July 2025, and in October 2025 renamed its parent company to Superhuman. So "Superhuman" now means both an email client (Superhuman Mail) and a Grammarly-descended productivity suite (the Superhuman Suite). This post is about the mail client only.

Where Superhuman Mail is not the right pick: no free tier at all, and the packaging is per-seat monthly or annual — check the live pricing page for current numbers, because they have moved. If you want $0 forever or a low-friction free trial you can walk away from before deciding, this is not the shape.

How to choose for your situation#

The choice compresses into three or four questions. Ask them in this order and you will land on one client, not eight.

1. 1

   Which mail providers do the Mac and the PC actually connect to?

   If both machines are pure Gmail, Shortwave is a valid answer and so are we. If one is Gmail and the other is Microsoft 365, Shortwave is out and eM Client, Spark, BlueMail, Superhuman Mail or AI Emaily are in. If one is an IMAP host that neither Google nor Microsoft owns, cross that off any Gmail-only or Google-and-Microsoft-only tool.

2. 2

   Do you want an AI agent, or classic mail with optional AI drafting?

   Agent with approval, undo, and an audit log: AI Emaily. Deep Gmail AI chat and semantic search: Shortwave, if you are Gmail-only. Drafting and summarize as an add-on: eM Client, Spark+, BlueMail's BlueAI. No AI at all: Thunderbird or classic Mailbird.

3. 3

   How much cross-machine state do you actually keep?

   If you have five rules and no snoozes and never edit signatures, Thunderbird's per-install profile is fine. If you have 40 rules, tuned snoozes, saved searches you rely on daily, and drafts that must be there on both machines by tomorrow morning, pick a client that syncs state through an account: any of the others on this list.

4. 4

   What does the budget look like?

   Zero forever, open source: Thunderbird. Free tier that is meaningful, then paid: eM Client, Spark, BlueMail, Shortwave. Paid only with a free trial: Superhuman Mail, Mailbird, AI Emaily. AI Emaily specifically is a 7-day free trial on Pro or Autopilot (card taken, $0 charged if you cancel before day 7); there is no public free plan. Full numbers on AI Emaily's pricing page.

A worked example: you use a MacBook (Apple Silicon) at home, a Windows 11 desktop at work, one Gmail account and one Microsoft 365 account, you snooze a lot, you keep about 30 filter rules, and you want AI to draft replies. Thunderbird is out because 30 rules per machine is too much to hand-copy. Shortwave is out because Microsoft 365. Superhuman Mail is a fit but paid-only with no free tier. eM Client, Spark and BlueMail all fit and lean on classic mail with add-on AI. AI Emaily is a fit and leans on an agent with an approval model. So the real narrowing is: do you want a chatbot-style draft assistant (Spark+, BlueAI, eM Client's AI add-on) or an inbox agent that also runs rules for you (AI Emaily)? That is the last honest fork.

One thing worth saying plainly: none of these clients works identically on Mac and Windows. Menu bars behave differently, keyboard shortcut mappings differ (Cmd on one, Ctrl on the other), and OS-level notification behavior is out of the app's hands. "Same client" here means same features, same account state, same triage decisions — not pixel-identical chrome. The clients that ship as Electron shells (AI Emaily, Shortwave, Superhuman Mail) come closest to pixel-identical because they render the same web view; the ones that use native toolkits (eM Client on each OS, Spark) look more at home on their respective OS but diverge more.