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Mailbird alternatives: 5 apps ranked by verified data

Facts checked Oct 25, 2026AppBreakup editorialHow we rank

Common reasons people leave Mailbird: no mobile apps, and free tier only covers one account. We ranked 5 alternatives by how directly each one replaces Mailbird, then by reviews, real visits and how recently each app's facts were checked against its own website. eM Client currently ranks first.

Quick comparison

#AppPricingOpen sourcePlatformsVerified factsScore
1eM Client logoeM ClientFree plan + paidNoWindows, macOS4 of 466.5
2Thunderbird logoThunderbirdOpen sourceYesWindows, macOS, Linux +15 of 562.6
3Spark logoSparkFree plan + paidNomacOS, Windows, iOS +13 of 359.6
4Mailspring logoMailspringFree plan + paidYesmacOS, Windows, Linux4 of 457.2
5Microsoft Outlook logoMicrosoft OutlookFree plan + paidNoWeb, Windows, macOS +23 of 355.3
  1. eM Client logo

    1. eM ClientTop pick

    Best for: Windows and Mac users who want Outlook-level features without Outlook

    Free plan + paidWindows, macOS

    66.5

    score / 100

    Why switch from Mailbird

    A deeper desktop client with calendar, tasks and PGP on Windows and Mac.

    Pros

    • Mail, calendar, tasks and contacts in one desktop app
    • Built-in PGP and strong Exchange support
    • Option to buy a one-time license

    Cons

    • Free version limited to home use and two accounts
    • No Linux version
    • Business licensing is per device
    Visit eM Client Details and reviews
    How this score is calculated
    Editorial fit ×0.3100
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is eM Client a good Mailbird alternative?

    Verified facts

    4 of 4 verified
    Free version
    Home use, 1 device, 2 accounts
    Checked Oct 25, 2026emclient.com(opens source in a new tab)
    Platforms
    Windows and macOS
    Checked Oct 25, 2026emclient.com(opens source in a new tab)
    Free trial
    30 days
    Checked Oct 25, 2026emclient.com(opens source in a new tab)
    License options
    Yearly subscription or one-time payment
    Checked Oct 25, 2026emclient.com(opens source in a new tab)
  2. Thunderbird logo

    2. Thunderbird

    Best for: Desktop users who want a free, private, customisable mail and calendar app

    Open sourceWindows, macOS, Linux, Android

    62.6

    score / 100

    Why switch from Mailbird

    Free and open source with unlimited accounts and add-ons.

    Pros

    • Free, open source and funded by donations, with no ads
    • Built-in OpenPGP, calendar, filters and many add-ons
    • Runs on Windows, Mac, Linux and Android

    Cons

    • No web version and no released iOS app yet
    • Add-ons sometimes break after major updates
    • Exchange setups can need extra configuration
    Visit Thunderbird Details and reviews
    How this score is calculated
    Editorial fit ×0.387
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Thunderbird a good Mailbird alternative?

    Verified facts

    5 of 5 verified
    Desktop platforms
    Windows, Linux, macOS
    Checked Oct 25, 2026thunderbird.net(opens source in a new tab)
    Price
    Free, funded by donations
    Checked Oct 25, 2026thunderbird.net(opens source in a new tab)
    Mobile app
    Open-source Android app
    Checked Oct 25, 2026thunderbird.net(opens source in a new tab)
    Android app origin
    Formerly K-9 Mail
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Android app license
    Apache-2.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
  3. Spark logo

    3. Spark

    Best for: People and small teams who want one smart inbox across all their devices

    Free plan + paidmacOS, Windows, iOS, Android

    59.6

    score / 100

    Why switch from Mailbird

    Free for unlimited accounts, with mobile apps as well as desktop.

    Pros

    • Free plan with unlimited accounts and a smart inbox
    • Shared threads, private comments and joint drafting for teams
    • Native apps on Mac, Windows, iOS and Android

    Cons

    • Mail syncs through Readdle's servers
    • Best AI and team features need a per-user subscription
    • No web app
    Visit Spark Details and reviews
    How this score is calculated
    Editorial fit ×0.377
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Spark a good Mailbird alternative?

    Verified facts

    3 of 3 verified
    Free plan
    Yes, unlimited email accounts
    Checked Oct 25, 2026sparkmailapp.com(opens source in a new tab)
    Plus price
    $10 per user/month (monthly)
    Checked Oct 25, 2026sparkmailapp.com(opens source in a new tab)
    Pro price
    $20 per user/month (monthly)
    Checked Oct 25, 2026sparkmailapp.com(opens source in a new tab)
  4. Mailspring logo

    4. Mailspring

    Best for: Desktop users, especially on Linux, who want a modern free client

    Free plan + paidOpen sourcemacOS, Windows, Linux

    57.2

    score / 100

    Why switch from Mailbird

    Open-source client with a free tier and Linux support.

    Pros

    • Free and open source on Mac, Windows and Linux
    • Clean interface with themes and keyboard shortcuts
    • Pro adds tracking, templates and send later at a low price

    Cons

    • No mobile apps
    • Small team, so features arrive slowly
    • Limited native Exchange support
    Visit Mailspring Details and reviews
    How this score is calculated
    Editorial fit ×0.369
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Mailspring a good Mailbird alternative?

    Verified facts

    4 of 4 verified
    License
    GPL-3.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Pro price
    $8 per month
    Checked Oct 25, 2026getmailspring.com(opens source in a new tab)
    Platforms
    Mac, Windows, Linux
    Checked Oct 25, 2026getmailspring.com(opens source in a new tab)
    Pro features
    Read receipts, link tracking, send later
    Checked Oct 25, 2026getmailspring.com(opens source in a new tab)
  5. Microsoft Outlook logo

    5. Microsoft Outlook

    Best for: People and companies already on Microsoft 365 or Exchange

    Free plan + paidWeb, Windows, macOS, iOS, Android

    55.3

    score / 100

    Why switch from Mailbird

    The new Outlook for Windows is free and handles Gmail and IMAP accounts too.

    Pros

    • Strongest calendar, scheduling and delegation features for Exchange users
    • Free Outlook.com mailbox kept separate from OneDrive storage
    • Apps on every major platform plus a solid web version

    Cons

    • Classic and new Outlook for Windows differ, which confuses users
    • Busy interface with many features most people never use
    • Free accounts show ads and get less storage
    Visit Microsoft Outlook Details and reviews
    How this score is calculated
    Editorial fit ×0.363
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Microsoft Outlook a good Mailbird alternative?

    Verified facts

    3 of 3 verified
    Free mailbox storage
    15 GB
    Checked Oct 25, 2026support.microsoft.com(opens source in a new tab)
    Free cloud storage
    5 GB (OneDrive and attachments)
    Checked Oct 25, 2026support.microsoft.com(opens source in a new tab)
    Microsoft 365 mailbox
    100 GB
    Checked Oct 25, 2026support.microsoft.com(opens source in a new tab)

The best Mailbird alternative for…

The highest-ranked app in this list for each need.

eM Client logo

Best Mailbird alternative for most people

eM Client

A deeper desktop client with calendar, tasks and PGP on Windows and Mac.

Thunderbird logo

Best Mailbird alternative for a free option

Thunderbird

Free and open source with unlimited accounts and add-ons.

Spark logo

Best Mailbird alternative for a free plan you can upgrade

Spark

Free for unlimited accounts, with mobile apps as well as desktop.

Mailspring logo

Best Mailbird alternative for open source

Mailspring

Open-source client with a free tier and Linux support.

Microsoft Outlook logo

Best Mailbird alternative for Mac

Microsoft Outlook

The new Outlook for Windows is free and handles Gmail and IMAP accounts too.

eM Client logo

Best Mailbird alternative for Windows

eM Client

A deeper desktop client with calendar, tasks and PGP on Windows and Mac.

Thunderbird logo

Best Mailbird alternative for Linux

Thunderbird

Free and open source with unlimited accounts and add-ons.

Spark logo

Best Mailbird alternative for iPhone and Android

Spark

Free for unlimited accounts, with mobile apps as well as desktop.

Microsoft Outlook logo

Best Mailbird alternative for working in the browser

Microsoft Outlook

The new Outlook for Windows is free and handles Gmail and IMAP accounts too.

Mailbird alternatives: common questions

What is the best alternative to Mailbird?

eM Client ranks first right now. A deeper desktop client with calendar, tasks and PGP on Windows and Mac. Thunderbird and Spark follow it in our ranking.

Is there a free alternative to Mailbird?

Yes. eM Client (free plan + paid), Thunderbird (open source), Spark (free plan + paid) and Mailspring (free plan + paid) have a free option. Check each app's verified facts for current plan limits.

Is there an open-source alternative to Mailbird?

Yes: Thunderbird and Mailspring.

Which Mailbird alternatives work on Linux?

Thunderbird and Mailspring run on Linux.

Why do people switch from Mailbird?

The complaints we hear most: no mobile apps; free tier only covers one account; integrations are mostly embedded web apps.

How is this list ranked?

Every app is scored with the same published formula: how directly it replaces Mailbird, reviews (weighted by verification), visits from AppBreakup, how recently its facts were checked against its own website, and reader votes.