Best Email Clients for Windows in 2026

Email on Windows has had its busiest couple of years in a decade. Microsoft killed the built-in Mail app at the end of 2024 and put the new Outlook in its place. Classic Outlook is on a long, slightly wobbly path to retirement. Microsoft is switching off the Exchange protocol that many third-party clients relied on, Postbox is gone, and Mailbird is between major versions. Most “best of” lists haven’t caught up with any of it.

This one covers the field as it stands in autumn 2026, and tells you which client fits the way you actually use email rather than crowning a single winner. (On Linux instead? See our Linux roundup.)

Quick picks

• Best for most people: Thunderbird
• Best zero-setup option: new Outlook
• Best for add-ins and corporate Microsoft 365: classic Outlook
• Best paid Outlook alternative: eM Client
• Best for a visual, board-style workflow: Kanmail
• Best for syncing phone and PC: Spark
• Best for Proton or Tuta users: their own desktop apps

How we picked

We didn’t install and live with every client for this roundup. Instead, each entry was checked against its maker’s current release notes, documentation and pricing pages, and against Microsoft’s own support and deployment docs for Outlook. Prices are US list prices before tax, as shown by each vendor in September 2026.

Where a product has changed hands, changed direction or died, we say so, because that’s the detail these lists most often get wrong. Last verified: September 2026. We revisit this post a few times a year.

New Outlook, the default you already have

If you’re here because Windows Mail stopped working, that was deliberate. Microsoft ended support for Mail, Calendar and People on 31 December 2024, and the apps no longer send or receive anything. Local mail from the old app can still be exported. In its place, Microsoft says Windows 11 devices now ship with the new Outlook “as the default mailbox application free for all to use”.

New Outlook is closely related to Outlook on the web, and it’s a different animal from the Outlook many offices grew up with. It handles Outlook.com and Microsoft 365 well, plus Gmail, Yahoo, iCloud and other IMAP accounts. For a Microsoft account with a calendar attached, it’s genuinely convenient.

There are two catches for free users. The first is ads: on a free account, Microsoft shows ads alongside your messages, marked with an “Ad” label. A Microsoft 365 subscription removes them, and the cheapest, Microsoft 365 Basic, is $19.99 a year.

The second is where your other accounts go. When you add a non-Microsoft account, new Outlook syncs copies of your mail, calendar and contacts through Microsoft’s data centres instead of connecting to your provider directly. When heise investigated in November 2023, it found IMAP and SMTP login details being sent to Microsoft’s servers, and Germany’s federal data protection commissioner said he would raise it with the Irish regulator that oversees Microsoft. If you’re adding a work IMAP account, check whether your employer is happy with a third party holding a copy.

Power users will also notice gaps. Microsoft’s own feature comparison, updated in September 2026, lists COM add-ins and VBA macros as not supported, and PST files and offline use as only partly available.

Pick it if: you mainly use Outlook.com or Microsoft 365, want nothing to install, and either pay for Microsoft 365 or don’t mind the ads.

Classic Outlook, on a long goodbye

Classic Outlook is still the most capable email program Microsoft makes: COM add-ins, PST archives, full offline mode, VBA and deep Exchange features. It isn’t free. You get it with a Microsoft 365 subscription (Personal is $99.99 a year in the US) or a one-time Office 2024 licence.

Its future is the confusing bit. Microsoft’s migration plan runs in three stages: opt-in, then opt-out (new Outlook on by default, with a toggle back), then cutover (no way back). For large organisations the opt-out stage was due in April 2026, but Microsoft pushed it to March 2027, with cutover no earlier than March 2028. It promises at least 12 months’ notice before each stage, and says existing classic installations “will continue to be supported until at least 2029”.

So there’s no rush, but the direction of travel is clear, and it leads to the web-based app.

Pick it if: your work depends on add-ins, PSTs or heavyweight Exchange features, or your IT department chooses your client for you. Our guide to organising an Outlook inbox covers both versions.

Thunderbird, still the free default

Thunderbird is the right first answer for most people on Windows, as it is on Linux. It’s free, open-source and funded by user donations, and it handles any number of accounts over IMAP or POP, with calendar, contacts and OpenPGP encryption built in. There’s a companion Android app too.

It comes in two flavours. The monthly Release channel was on version 156 at the end of September 2026, and the annual Extended Support Release is 153 “Meadow”, out in July. thunderbird.net offers a standard installer and an MSI for managed deployments, and the ESR is also in the Microsoft Store.

The big 2026 story for Windows users is Exchange. Thunderbird now talks to Exchange natively with no add-on, via Exchange Web Services (EWS), which reached the ESR with 153. But Microsoft is phasing out EWS on Microsoft 365 from October 2026, so Thunderbird added Microsoft Graph support in Release 154. If your work mail is on Microsoft 365, that means running the monthly channel rather than the ESR, and for now Graph covers email only, with no Exchange calendar or address book yet. On-premises Exchange and plain IMAP users don’t need to change anything.

The usual criticism still applies: with everything switched on it feels busy, and the settings sprawl.

Pick it if: you want one dependable, free client for every account and don’t mind a little tweaking. (How Thunderbird compares to Kanmail, if you want a paid alternative side by side.)

Betterbird, the fork on the slower track

Betterbird is a Thunderbird fork that adds fixes and features upstream hasn’t taken, often around folders, search and the message list. It follows the ESR line (the current build is 153.3.0esr-bb9, from 16 September 2026), ships a Windows installer and a portable version, and is on winget and Chocolatey. It’s free, with donations welcome.

It’s worth it if Betterbird has already fixed a specific Thunderbird annoyance of yours. Because it’s built on the ESR rather than the monthly channel, check its Microsoft Graph status before relying on it for Microsoft 365 mail once EWS goes.

eM Client, the Outlook alternative with a calendar

eM Client is what most people mean when they ask for “Outlook, but not from Microsoft”. It’s a traditional desktop app from a Prague-based company, with mail, calendar, contacts, tasks and chat in one window, strong Gmail and Exchange support, and PGP and S/MIME encryption. It runs on Windows and Mac, and its iOS and Android apps are free.

Pricing, in the US in September 2026:

• Free: personal, non-commercial use only, two email accounts on one device. Thread view, snooze, send later, undo send and tracking-pixel detection are paid features.
• Personal: $59.95 once for up to three devices, or $39.95 a year.
• Business: $79.95 per device once, or $49.95 a year.

A one-time licence covers the major version you buy (currently 10) and its point releases. Moving to the next major version is an upgrade you pay for, although you can keep using the version you have indefinitely.

That detail matters this year. eM Client faces the same EWS retirement as everyone else on Microsoft 365, and its staff said in July 2026 that the switch to Microsoft Graph is planned for eM Client 11. If Microsoft 365 over Exchange is your reason for buying, check where that stands and whether your licence will cover it.

Pick it if: you want an Outlook-shaped app with a real calendar and would rather pay once than subscribe.

Kanmail, if you want a board instead of a list

Full disclosure: this is our client, so weigh this section accordingly. It’s here because it does something none of the others do.

Kanmail turns your inbox into a kanban board. Every email is a card, the columns are your folders or Gmail labels, and dragging a card from one column to another moves the message on the server too. All your accounts share one board with a colour accent each, and you can save different column layouts as workflows and switch between them. Every other client here is some variation on a chronological list. (How the kanban approach works.)

On Windows it’s a standard installer for 64-bit Windows 10 and later. Outlook.com and Microsoft 365 connect through Microsoft’s own sign-in page, Gmail through Google’s, and anything else over IMAP. Work and school Microsoft accounts may need an IT admin to approve the app first. Kanmail reads Microsoft 365 mail over IMAP rather than EWS, so the Exchange shutdown doesn’t affect it.

It’s local-first: mail goes straight from your provider to your PC and is never copied to our servers, and tracking pixels are stripped. There’s one-click unsubscribe, sender colour-coding and keyboard shortcuts throughout, and the app is source-available.

The trade-offs, honestly: it costs $49 (once, not a subscription), there’s no mobile app, and it’s mail only, so keep Outlook or another app for your calendar.

Pick it if: you juggle several accounts or a lot of threads in flight and want to see where everything stands at a glance, and you’d rather own your client than rent it. (Kanmail with Outlook, in detail.)

Spark, for the same inbox on phone and PC

Spark from Readdle is the pick if your email life is split between phone and desktop. It runs on Windows, Mac, iOS and Android, synced across all of them, and the free plan is genuinely usable: unlimited accounts, a Smart Inbox that separates personal mail from notifications and newsletters, and a calendar.

The paid tiers are where the AI and team features live. Plus is $99 a year and Pro is $199, or $10 and $20 month to month.

That cross-device sync comes from Readdle’s side. You sign in to a Spark account, and Spark’s privacy policy says your mailbox credentials are stored as a token, and that while mail is “mainly processed on your device”, features such as send later, shared emails and shared drafts are processed on its servers. That’s a fair trade for what you get, but it’s a different model from a purely local client.

Pick it if: you want one polished app across phone and PC and like having your inbox pre-sorted. (Spark vs Kanmail, and switching from Spark.)

Mailbird, between versions

Mailbird has been a Windows favourite since the early 2010s, known for a clean unified inbox with other apps docked in a sidebar. It’s on Mac too now, and a licence covers both.

The free plan allows one account. Premium is about $4 a month billed yearly, or $99.75 for a “Pay Once” licence (advertised as 75% off), with lifetime updates sold as an optional extra.

The bigger news is structural. In a September 2026 post, Mailbird’s CEO announced that Mailbird 2 stops receiving updates, security fixes included, at the end of 2026, and that every Mailbird 2 customer gets a free upgrade to Mailbird 3. He also apologised: earlier “Pay Once” and “Lifetime” wording led many buyers to expect every future version, when Mailbird meant updates within Mailbird 2 only. Mailbird 3 will get “minor updates and fixes for now” while the company finishes Mailbird Next, a new cross-platform version with mobile apps that the post implied was planned for around October 2026.

Credit to them for owning it. It does mean you’re buying into a product on the cusp of a major version change.

Pick it if: you want a unified inbox with app integrations and don’t mind waiting to see what Mailbird Next turns out to be. (Switching from Mailbird.)

Superhuman Mail, now part of a bigger suite

Superhuman built its name on speed: keyboard-first, meticulously designed, and expensive. It works with Gmail and Outlook accounts only, and it has a Windows desktop app as well as a Mac one.

The company around it has changed. Grammarly bought Superhuman in July 2025, then took the name for the whole business: Grammarly, Coda (now Superhuman Docs) and Superhuman Mail now sit under one Superhuman brand, alongside an AI assistant called Superhuman Go. Mail costs $25 per user per month on the Starter plan and $33 on Business, both billed annually.

That’s at least $300 a year. If AI triage and drafting are central to your day and someone else is paying, it can earn that. Otherwise it’s the priciest seat on this list, and a good example of why we’re wary of renting a mail client.

Pick it if: you’re on Gmail or Microsoft 365, live in email all day, and want AI doing a share of the work. (Superhuman vs Kanmail.)

Proton Mail and Tuta, for their own accounts

Both encrypted-email services have Windows desktop apps, with the caveat that each only works with its own accounts. The Proton Mail desktop app needs Windows 10 or later and a paid Proton plan; free users get a 14-day trial. Using Proton in Outlook or Thunderbird instead means Proton Mail Bridge, which is also paid-only. Tuta is more generous: its desktop apps are included on the free plan.

Pick them if: you already use Proton or Tuta and want a proper desktop app for it. (Proton Mail on a kanban board works through Bridge.)

Honourable mentions

• Mailspring: a free, modern-looking client that went quiet for a while and is shipping regularly again, with version 1.25 released in September 2026. Read receipts, send later, snooze and templates need Mailspring Pro at $8 a month.
• BlueMail: free for personal use with unlimited accounts, available in the Microsoft Store, and the same app on your phone. Paid Plus and Team plans add AI and business features.

What we left out, and why

Windows Mail and Calendar. Dead since 31 December 2024, as above. If an old guide recommends them, it’s out of date.

Postbox. A polished, paid, Thunderbird-based client with a loyal following. On 22 October 2024 its makers announced that Postbox had been acquired by eM Client and “will no longer be sold or developed”. Support ended on 22 December 2024, and users were pointed to eM Client with a discount that ran until 31 January 2025. The app still opens, but a mail client with no security updates isn’t somewhere to keep reading your email. If you’re still on it, eM Client and Thunderbird are the natural moves.

Comparison at a glance

The bottom line

For most Windows users, Thunderbird is the right first move: free, capable, and now fluent in Exchange, as long as Microsoft 365 users stay on the monthly channel. If your life runs on Microsoft 365, Outlook is the path of least resistance, and classic Outlook isn’t going anywhere before 2029. eM Client is the best paid alternative if you want mail and calendar in one app and would rather pay once. Choose Kanmail if what you actually want is to see your email as work in progress: a board that puts every account in one view and turns triage into drag-and-drop.

Try Kanmail on Windows: free to evaluate, no time limit, no subscription.