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Posteo alternatives: 5 apps ranked by verified data

Facts checked Oct 25, 2026AppBreakup editorialHow we rank

Common reasons people leave Posteo: no custom domains, and plain web interface and no own mobile apps. We ranked 5 alternatives by how directly each one replaces Posteo, then by reviews, real visits and how recently each app's facts were checked against its own website. mailbox.org currently ranks first.

Quick comparison

#AppPricingOpen sourcePlatformsVerified factsScore
1mailbox.org logomailbox.orgPaidNoWeb4 of 466.5
2Tuta logoTutaFree plan + paidYesWeb, Windows, macOS +34 of 462.6
3Proton Mail logoProton MailFree plan + paidYesWeb, Windows, macOS +35 of 559.6
4Fastmail logoFastmailPaidNoWeb, iOS, Android5 of 557.2
5Mailfence logoMailfenceFree plan + paidNoWeb3 of 355.3
  1. mailbox.org logo

    1. mailbox.orgTop pick

    Best for: European individuals and businesses who want private email and office tools in one place

    PaidWeb

    66.5

    score / 100

    Why switch from Posteo

    Another German provider at a similar price, but with custom domains and an office suite.

    Pros

    • Low per-user prices with custom domains
    • Data stored in Germany with PGP options
    • Includes calendar, cloud storage, office suite and meetings

    Cons

    • Web interface feels dated
    • No dedicated mobile apps
    • No free plan
    Visit mailbox.org 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 mailbox.org a good Posteo alternative?

    Verified facts

    4 of 4 verified
    Light plan
    €1 per user/month (2 GB)
    Checked Oct 25, 2026mailbox.org(opens source in a new tab)
    Standard plan
    €4 per user/month (20 GB)
    Checked Oct 25, 2026mailbox.org(opens source in a new tab)
    Free trial
    30 days
    Checked Oct 25, 2026mailbox.org(opens source in a new tab)
    Data location
    Germany
    Checked Oct 25, 2026mailbox.org(opens source in a new tab)
  2. Tuta logo

    2. Tuta

    Best for: People who want the most encryption for the least money and accept using Tuta's own apps

    Free plan + paidOpen sourceWeb, Windows, macOS, Linux, iOS, Android

    62.6

    score / 100

    Why switch from Posteo

    End-to-end encrypted with its own apps and a free plan.

    Pros

    • Encrypts subjects, contacts and calendars, not just bodies
    • Open-source apps on desktop, mobile and web
    • Low-cost paid plans with custom domains

    Cons

    • No IMAP, so third-party mail apps are not supported
    • Search and filtering are basic
    • Free plan has very little storage
    Visit Tuta 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 Tuta a good Posteo alternative?

    Verified facts

    4 of 4 verified
    Storage (Free / Revolutionary / Legend)
    1 GB / 20 GB / 500 GB
    Checked Oct 25, 2026tuta.com(opens source in a new tab)
    Encryption
    End-to-end, post-quantum
    Checked Oct 25, 2026tuta.com(opens source in a new tab)
    Family member add-on
    €3 per user/month (Revolutionary)
    Checked Oct 25, 2026tuta.com(opens source in a new tab)
    License
    GPL-3.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
  3. Proton Mail logo

    3. Proton Mail

    Best for: Privacy-minded people and teams who want encrypted email without running servers

    Free plan + paidOpen sourceWeb, Windows, macOS, Linux, iOS, Android

    59.6

    score / 100

    Why switch from Posteo

    Encrypted email with polished apps on every platform.

    Pros

    • End-to-end and zero-access encryption by default
    • Open-source, audited apps on every major platform
    • Bundles with Proton VPN, Drive, Calendar and Pass

    Cons

    • Free plan has little storage and one address
    • Search and third-party integrations are more limited than Gmail
    • Using desktop clients needs the paid Bridge app
    Visit Proton Mail 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 Proton Mail a good Posteo alternative?

    Verified facts

    5 of 5 verified
    Free plan
    Yes
    Checked Oct 25, 2026proton.me(opens source in a new tab)
    Mail Plus price
    $4.99/month, or $3.99/month billed yearly
    Checked Oct 25, 2026proton.me(opens source in a new tab)
    Jurisdiction
    Switzerland
    Checked Oct 25, 2026proton.me(opens source in a new tab)
    Open source
    Yes, independently audited
    Checked Oct 25, 2026proton.me(opens source in a new tab)
    License (web clients)
    GPL-3.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
  4. Fastmail logo

    4. Fastmail

    Best for: People and families who want private, ad-free email on their own domain

    PaidWeb, iOS, Android

    57.2

    score / 100

    Why switch from Posteo

    Costs more, but adds custom domains, a faster web app and mobile apps.

    Pros

    • Fast web app with excellent search
    • Masked Email aliases and easy custom domains
    • Standard IMAP, CalDAV and JMAP support for any client

    Cons

    • No free plan
    • Not end-to-end encrypted
    • No desktop apps of its own
    Visit Fastmail 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 Fastmail a good Posteo alternative?

    Verified facts

    5 of 5 verified
    Free trial
    30 days
    Checked Oct 25, 2026fastmail.com(opens source in a new tab)
    Founded
    1999
    Checked Oct 25, 2026fastmail.com(opens source in a new tab)
    Headquarters
    Melbourne, Australia
    Checked Oct 25, 2026fastmail.com(opens source in a new tab)
    Masked Email
    Yes
    Checked Oct 25, 2026fastmail.com(opens source in a new tab)
    Data location
    EU or USA
    Checked Oct 25, 2026fastmail.com(opens source in a new tab)
  5. Mailfence logo

    5. Mailfence

    Best for: Users who want OpenPGP encryption that works with other PGP tools

    Free plan + paidWeb

    55.3

    score / 100

    Why switch from Posteo

    Belgian private email with a free tier and OpenPGP built in.

    Pros

    • OpenPGP encryption and signatures built in
    • Works with standard mail clients via IMAP and POP
    • Includes calendar, contacts and documents

    Cons

    • PGP key management has a learning curve
    • Plain, utilitarian interface
    • Free plan is small
    Visit Mailfence 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 Mailfence a good Posteo alternative?

    Verified facts

    3 of 3 verified
    Free plan
    1 GB
    Checked Oct 25, 2026mailfence.com(opens source in a new tab)
    Jurisdiction
    Belgium
    Checked Oct 25, 2026mailfence.com(opens source in a new tab)
    Encryption
    OpenPGP
    Checked Oct 25, 2026mailfence.com(opens source in a new tab)

The best Posteo alternative for…

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

mailbox.org logo

Best Posteo alternative for most people

mailbox.org

Another German provider at a similar price, but with custom domains and an office suite.

Tuta logo

Best Posteo alternative for a free plan you can upgrade

Tuta

End-to-end encrypted with its own apps and a free plan.

Proton Mail logo

Best Posteo alternative for open source

Proton Mail

Encrypted email with polished apps on every platform.

Tuta logo

Best Posteo alternative for Mac

Tuta

End-to-end encrypted with its own apps and a free plan.

Tuta logo

Best Posteo alternative for Windows

Tuta

End-to-end encrypted with its own apps and a free plan.

Tuta logo

Best Posteo alternative for Linux

Tuta

End-to-end encrypted with its own apps and a free plan.

Fastmail logo

Best Posteo alternative for iPhone and Android

Fastmail

Costs more, but adds custom domains, a faster web app and mobile apps.

Mailfence logo

Best Posteo alternative for working in the browser

Mailfence

Belgian private email with a free tier and OpenPGP built in.

Posteo alternatives: common questions

What is the best alternative to Posteo?

mailbox.org ranks first right now. Another German provider at a similar price, but with custom domains and an office suite. Tuta and Proton Mail follow it in our ranking.

Is there a free alternative to Posteo?

Yes. Tuta (free plan + paid), Proton Mail (free plan + paid) and Mailfence (free plan + paid) have a free option. Check each app's verified facts for current plan limits.

Is there an open-source alternative to Posteo?

Yes: Tuta and Proton Mail.

Which Posteo alternatives work on Linux?

Tuta and Proton Mail run on Linux.

Why do people switch from Posteo?

The complaints we hear most: no custom domains; plain web interface and no own mobile apps; no free plan.

How is this list ranked?

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