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eM Client alternatives: 5 apps ranked by verified data

Facts checked Oct 25, 2026AppBreakup editorialHow we rank

Common reasons people leave eM Client: free version limited to home use and two accounts, and no Linux version. We ranked 5 alternatives by how directly each one replaces eM Client, then by reviews, real visits and how recently each app's facts were checked against its own website. Microsoft Outlook currently ranks first.

Quick comparison

#AppPricingOpen sourcePlatformsVerified factsScore
1Microsoft Outlook logoMicrosoft OutlookFree plan + paidNoWeb, Windows, macOS +23 of 366.5
2Thunderbird logoThunderbirdOpen sourceYesWindows, macOS, Linux +15 of 562.6
3Spark logoSparkFree plan + paidNomacOS, Windows, iOS +13 of 355.3
  1. Microsoft Outlook logo

    1. Microsoft OutlookTop pick

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

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

    66.5

    score / 100

    Why switch from eM Client

    The standard choice if you need full Exchange and Microsoft 365 features.

    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 ×0.3100
    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 Microsoft Outlook a good eM Client 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)
  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 eM Client

    Free and open source, with calendars and OpenPGP, also on Linux.

    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 eM Client 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

    55.3

    score / 100

    Why switch from eM Client

    Adds mobile apps and team collaboration across platforms.

    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 ×0.363
    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 Spark a good eM Client 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)

The best eM Client alternative for…

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

Microsoft Outlook logo

Best eM Client alternative for most people

Microsoft Outlook

The standard choice if you need full Exchange and Microsoft 365 features.

Thunderbird logo

Best eM Client alternative for a free option

Thunderbird

Free and open source, with calendars and OpenPGP, also on Linux.

Mailbird logo

Best eM Client alternative for a free plan you can upgrade

Mailbird

A Windows and Mac client focused on app integrations and a unified inbox.

Mailspring logo

Best eM Client alternative for open source

Mailspring

Open-source desktop client that also runs on Linux.

Spark logo

Best eM Client alternative for Mac

Spark

Adds mobile apps and team collaboration across platforms.

Microsoft Outlook logo

Best eM Client alternative for Windows

Microsoft Outlook

The standard choice if you need full Exchange and Microsoft 365 features.

Thunderbird logo

Best eM Client alternative for Linux

Thunderbird

Free and open source, with calendars and OpenPGP, also on Linux.

Microsoft Outlook logo

Best eM Client alternative for iPhone and Android

Microsoft Outlook

The standard choice if you need full Exchange and Microsoft 365 features.

Microsoft Outlook logo

Best eM Client alternative for working in the browser

Microsoft Outlook

The standard choice if you need full Exchange and Microsoft 365 features.

eM Client alternatives: common questions

What is the best alternative to eM Client?

Microsoft Outlook ranks first right now. The standard choice if you need full Exchange and Microsoft 365 features. Thunderbird and Mailbird follow it in our ranking.

Is there a free alternative to eM Client?

Yes. Microsoft Outlook (free plan + paid), Thunderbird (open source), Mailbird (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 eM Client?

Yes: Thunderbird and Mailspring.

Which eM Client alternatives work on Linux?

Thunderbird and Mailspring run on Linux.

Why do people switch from eM Client?

The complaints we hear most: free version limited to home use and two accounts; no Linux version; business licensing is per device.

How is this list ranked?

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