Email Clients for Windows (2026): 6 Desktop Apps Compared

A browser tab full of inboxes works until you're running three accounts, a calendar and a stack of invites at once. A desktop mail app brings it together in one window, keeps your mail searchable offline and gives you rules, shortcuts and signatures that a webmail tab won't.

The six apps below are listed alphabetically and in no particular order. Each description comes from the app's own website, and every one of them runs on Windows. This list is about the desktop app you read your mail in, not the provider that hosts your address.

Windows mail apps compared

Tool	Type	Good for
Betterbird	Fine tuned open source fork	Trying extra fixes without leaving your current profile
eM Client	Desktop mail, calendar and contacts with AI	Drafted replies, summaries and plain language search
Mailbird	Unified inbox desktop app	Every account in one inbox, with apps in a side panel
Mailspring	Native mail client for three systems	Fast search across accounts, undo send and send later
Postbox	Power user email app	Keyboard driven triage and a customisable layout
Thunderbird	Open source email, calendar and contacts	A unified inbox with no ads, funded by donations

Six desktop email apps for Windows

Betterbird

Best for: People who like the Mozilla mail client but want extra features and fixes; the page says it installs beside the original and runs on the same profile.

eM Client

Best for: Professionals who want an AI assistant in the sidebar that can find an old email, tidy a folder or draft a reply from a plain request.

Mailbird

Best for: Anyone juggling several accounts who wants one unified inbox, with a calendar and task apps in a side panel; the page names a free start.

Mailspring

Best for: Users on more than one operating system who want a native app with several accounts, read receipts, link tracking and send later.

Postbox

Best for: Keyboard fans who want quick actions, a full set of shortcuts, filters and rules, and a layout they can customise panel by panel.

Thunderbird

Best for: Privacy minded users who want an open source app with messages, calendars and contacts together, and accounts kept separate or in a unified inbox.

Two of these aren't independent any more

Before you compare features, know who owns what. Postbox's page says it has been acquired by eM Client, so the two now sit under one company. And Betterbird describes itself as a fine tuned version of Mozilla Thunderbird, with new features and bug fixes of its own, plus fixes the original may ship at a later stage.

That second point is handy if you're unsure which way to go. The fork's page says you can install it at the same time as the original and run them on the same profile, then go back if you don't like it. That makes it the lowest friction way to compare the two, without moving a single message, and its page also mentions a portable version for Windows.

Commercial polish or open source freedom?

The commercial clients compete on extras. Mailbird's page says it brings all your email accounts into one desktop app that's quick, private and intuitive, with integrations such as WhatsApp, Google Calendar, Asana and Dropbox in a side panel, and it names a free start with a Premium tier. Mailspring describes a native desktop app for Mac, Windows and Linux, with support for several accounts, read receipts, link tracking and send later, and says it's free for everything you need, with Pro features on top.

One commercial client on this list now leads with AI: an assistant in the sidebar, replies drafted in one click, summaries of long threads and search in plain language. Its page also says you can connect your own AI provider, which matters if you'd rather choose who reads your mail.

The open source route is different in spirit. The open source client on this list says it's funded by user donations, doesn't sell ads in your inbox and lets you manage accounts separately or in a unified inbox. You give up some of the polish and the AI extras, and you get an app that's free forever and easy to customise.

Features worth checking before you switch

• Account types. Gmail, iCloud, Yahoo and any IMAP account, plus Exchange if you use it at work.
• Unified inbox and search. One inbox for every account, and one search that covers all of them at once.
• Calendar and contacts. Both in the same app, so an invite doesn't send you back to the browser.
• Where your mail lives. Stored on your own computer or synced through the vendor's servers.
• Tracking and privacy. Read receipts for what you send, and blocking of tracking pixels in what you receive.
• AI features. What they can see, whether you can switch them off, and whether you can bring your own provider.
• Updates. One fork's page warns against old versions because they have unpatched security vulnerabilities, so keep whichever app you choose up to date.

Thinking of leaving the mail app that came with work? My list of Outlook alternatives covers the wider set of options.

Moving to a new desktop client without losing mail

1. Check your accounts use IMAP or Exchange, so your mail stays on the server and syncs to the new app.
2. Write down the rules, filters and signatures you rely on, because they rarely move across on their own.
3. Install the new client and add one account first, then let it finish syncing before you add the rest.
4. Run the old and new apps side by side for a week, sending and receiving from both.
5. Export your contacts and calendars from the old app if they aren't stored with your email provider.
6. Only uninstall the old client once search, folders and sent mail all look right in the new one.

Do you make desktop email clients or inbox tools? Tool makers can ask to be considered for a featured place on this list.

My plain advice for choosing a Windows mail app

Start with the free route and only add the extras you'll use. If you want a simple open source client that keeps your calendar and contacts together, that's covered without ads. If you'd like AI drafting and summaries built in, try a commercial client that leads with them. And if you already use the Mozilla client but want a few more fixes, installing the fork beside it's the easiest test you'll run.

Want help with the writing rather than the app? My list of AI email assistants covers tools that draft and sort for you, and my guide to email apps for iPhone helps you match your phone to your desktop.

Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.

For the adjacent case, read Best AI Assistants for Windows (2026): 10 Desktop Apps.

Frequently asked questions

What's the best free email client for Windows?

Several clients on this list say you can download them free, including an open source app funded by donations. The right one depends on whether you want AI and integrations or a simple, private inbox.

Do I need a desktop email client if I use webmail?

You don't need one, but a desktop app puts every account in one window, keeps your mail searchable offline and adds rules, shortcuts and signatures that work across all your addresses.

Can I use several email accounts in one Windows app?

Yes. Every app on this list says it supports several accounts, and most offer a unified inbox so you can read and reply from one place.

Is an open source email client safe to use?

Open source means the code is public, and many people use these apps every day. Whatever you choose, keep it updated, because old versions can carry unpatched security problems.

Will I lose my emails if I switch email client?

Not if your accounts use IMAP or Exchange, because your mail stays on the server. Check rules, signatures and local folders before you uninstall the old app.

What's a fork of an email client?

A fork is a separate project built from another app's open source code. It keeps the original's core and adds its own features and fixes, and some can run beside the original.