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Head-to-head · Email Apps

Mozilla Thunderbird vs Proton Mail

  • Updated Oct 2026
  • Both researched from official sources
  • 3 checks side by side
Higher score Mozilla Thunderbird #3 in Email Apps 9.2/10 Free plan Free plan✓ 1 of 3 features Visit Thunderbird
Proton Mail #5 in Email Apps 9.0/10 Free plan Free planFree trial✓ 1 of 3 features Visit Proton Mail

Mozilla Thunderbird leads on 0 checks, Proton Mail on 0, and 3 are even. Who comes out ahead on the 3 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scoreMozilla Thunderbird · 9.2/10
  • Free planboth
  • Free trialonly Proton Mail

Mozilla Thunderbird scores higher on our rubric for email apps: 9.2 against 9.0 out of 10; our editors rank them #3 and #5.

Mozilla Thunderbird is the better fit for free, open-source email across desktop and Android. Proton Mail is the better fit for privacy-focused users wanting encrypted email.

  • Mozilla Thunderbird fits best

    Free, open-source email across desktop and Android

  • Proton Mail fits best

    Privacy-focused users wanting encrypted email

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Side by side

Feature Mozilla Thunderbird 9.2/10 Visit ↗ Proton Mail 9.0/10 Visit ↗
At a glance
Editor score 9.2 9.0
Ranking #3 in Email Apps #5 in Email Apps
Best for Free, open-source email across desktop and Android Privacy-focused users wanting encrypted email
Pricing model Free Free plan + paid
Starting price Free $3.99/user/mo
Free plan ✓ ✓
Free trial — 14 days
Deployment Desktop, Mobile Cloud, Desktop, Mobile
Platforms Windows, macOS, Linux, Android Web, Windows, macOS, Linux, iOS, Android
Support Community, Docs Email, Live chat, Tickets, Docs
Built for Solo, Small business, Mid-market, Enterprise Solo, Small business, Mid-market, Enterprise
Features Mozilla Thunderbird 1/3 · Proton Mail 1/3
Unified inbox ✓ (best) Not checked yet
End-to-end encryption Not checked yet Not checked yet
Custom domains Not checked yet ✓ (best)
Specs
Accounts supported Not checked yet Not checked yet
Platforms Not checked yet Not checked yet
Included storage Not checked yet Not checked yet
Our review
Pros
  • Manage multiple accounts in a unified inbox with search and message organization
  • Includes calendar, contacts, tasks, and offline local message storage
  • Open-source client supports OpenPGP encryption and add-ons
  • Encrypts messages between Proton Mail users and stored mailbox content
  • Sends password-protected encrypted emails to non-Proton recipients
  • Offers custom domains and hide-my-email aliases on paid plans
Cons
  • Scheduled sending requires the Send Later add-on
  • Support is through community resources and documentation
  • Desktop apps are limited to Windows, macOS, and Linux
  • Free plan includes 1 GB storage and one encrypted email address
  • Custom domains require a paid plan
  • Desktop email-client access uses Proton Mail Bridge
Our verdict

Mozilla Thunderbird is a free, open-source email client for individuals and organizations. Its desktop applications run on Windows, macOS, and Linux, and Thunderbird Mobile is available for Android. Multiple-account support and a unified…

Read the review →

Proton Mail centers on private email for individuals, families, and organizations that want encryption and tracking protection in their mailbox. Messages between Proton Mail users are end-to-end encrypted, and stored messages and…

Read the review →
  1. Mozilla ThunderbirdEmail Apps 9.2Free plan
  2. Proton MailEmail Apps 9.0Free plan

Strengths and trade-offs

  • Mozilla Thunderbird — where it wins

    • Manage multiple accounts in a unified inbox with search and message organization
    • Includes calendar, contacts, tasks, and offline local message storage
    • Open-source client supports OpenPGP encryption and add-ons

    Where it doesn't

    • Scheduled sending requires the Send Later add-on
    • Support is through community resources and documentation
    • Desktop apps are limited to Windows, macOS, and Linux

  • Proton Mail — where it wins

    • Encrypts messages between Proton Mail users and stored mailbox content
    • Sends password-protected encrypted emails to non-Proton recipients
    • Offers custom domains and hide-my-email aliases on paid plans

    Where it doesn't

    • Free plan includes 1 GB storage and one encrypted email address
    • Custom domains require a paid plan
    • Desktop email-client access uses Proton Mail Bridge

More comparisons

All email apps comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update