Encryption27 of 27
Trust and audits18 of 26
Apps and access16 of 18
Mailbox12 of 13
Price12 of 16
encrypted email service · Proton AG
Proton Mail
Swiss encrypted mailbox with a free plan, open-source apps and a paid bridge for desktop mail programs.
In short
- The free plan gives one mailbox with 1 GB of storage once the setup checklist is done1.
- Mail Plus costs $3.99 a month on yearly billing and adds 15 GB and 1 custom domain1.
- Stored messages use zero-access encryption, so Proton cannot read them2.
- Bridge, which connects Outlook or Thunderbird, works only on paid plans1,4.
- Proton's transparency report for 2025 counts 9,301 legal orders for Proton Mail3.
Proton Mail suits people who want zero-access storage, a free starter mailbox and open-source apps1,2,6. Mail Plus at $3.99 a month adds a custom domain and Bridge for desktop mail programs1,4. The catch: Bridge is paid-only, the Linux app is still beta, and no outside audit of the mail apps dated 2024 or later is named on the vendor's open-source page1,4,5.
Best for: People who want a free encrypted mailbox that grows into a paid one with custom domains and Outlook or Thunderbird access.
Where the points come from
Encryption 27 of 27 points
| Rule | What is published | Points |
|---|---|---|
| Stored mail the provider cannot read | YesProton says messages and attachments in the inbox use zero-access encryption, so nobody, not even Proton, can access them2. | 10 / 10 |
| Automatic end-to-end encryption between its own users | YesProton says messages between Proton Mail addresses are always end-to-end encrypted2. | 8 / 8 |
| Encrypted mail to other providers | YesPassword-protected emails send end-to-end encrypted messages to non-Proton addresses2. | 6 / 6 |
| Encrypted contacts or calendar | YesProton says Calendar event details are end-to-end encrypted so Proton cannot see them10. | 3 / 3 |
Trust and audits 18 of 26 points
| Rule | What is published | Points |
|---|---|---|
| Independent audit since 2024 | Not publishedThe open-source page links audit reports but names no firm or date5; the named Securitum audit is dated 202111. | 0 / 8 |
| Open-source apps | YesProton says all its apps are open source; the web clients are on GitHub under GPL-3.05,6. | 6 / 6 |
| SOC 2 Type II or ISO 27001 | YesProton received ISO 27001 certification on 2 May 2024, covering its information security management systems9. | 4 / 4 |
| Transparency report | YesThe report gives Proton Mail legal order counts for 2025: 9,301 orders, 988 contested3. | 4 / 4 |
| Security key for two-factor sign-in | YesProton accepts a physical U2F or FIDO2 security key for two-factor sign-in, on free and paid plans7. | 4 / 4 |
Apps and access 16 of 18 points
| Rule | What is published | Points |
|---|---|---|
| Official apps | Windows, macOS, iOS, AndroidDownload page lists Windows, macOS, iOS and Android apps; the Linux app is labelled beta, so it does not count4. Free accounts get a 14-day desktop trial13. | 8 / 10 |
| Works in standard mail programs | YesBridge, Proton's own desktop app, links paid accounts to Outlook, Thunderbird and Apple Mail1,4,12. | 8 / 8 |
Mailbox 12 of 13 points
| Rule | What is published | Points |
|---|---|---|
| Your own domain | YesMail Plus supports 1 custom domain; Unlimited supports 31. | 5 / 5 |
| Mail storage on the cheapest paid plan | 15Mail Plus, the cheapest paid plan, has 15 GB1. | 4 / 5 |
| Export your whole mailbox | YesThe Export Tool saves all emails as EML files with JSON metadata; Bridge also copies the mailbox to a mail program8. | 3 / 3 |
Price 12 of 16 points
The rule behind each line: how we score encrypted email services.
Plans and prices
As the vendor lists them, before tax. Prices are in US dollars unless the plan shows euros; the points use US dollars, with euros converted at the ECB rate.
| Plan | Price as listed | Per month | Notes |
|---|---|---|---|
| Free1 person | Free1 | $0 | 1 email address; 500 MB, 1 GB after the setup checklist |
| Mail Plus1 person | $47.88/year1,4 | $3.99 | 15 GB, 1 custom domain, Bridge; $4.99 on monthly billing |
| Proton Unlimited1 person | $119.88/year1 | $9.99 | 500 GB shared across Proton apps, 3 custom domains; $12.99 on monthly billing |
Prices are shown in US dollars, before tax. The pricing page lists only 1-month and 12-month billing1.
Strengths
- Documents zero-access encryption of stored mail and encrypted calendar events2,10.
- Sends password-protected encrypted mail to people on other providers2.
- The transparency report covers 2025 and gives order counts3.
- Names an ISO 27001 certification, dated May 20249.
- Physical U2F or FIDO2 security keys protect sign-in7.
Limits
- Free storage is 500 MB, rising to 1 GB after a setup checklist1.
- Bridge for desktop mail programs needs a paid plan1,4.
- The Linux app is labelled beta4.
- Subject lines and email addresses are not end-to-end encrypted2.
- Free accounts can try the Windows and macOS desktop apps for 14 days; after that they need a paid plan13.
What Proton AG says
Vendor claims. We show them, but they earn no points.
- Proton says all its apps are open source and independently audited by third-party experts5.
Other encrypted email services
- 2
Tuta MailPeople who want contacts and calendar encrypted too, and are fine using Tuta's own apps instead of a mail program73/100$3.36/mocheapest paid plan - 3
Forward EmailPeople with their own domain who want IMAP access and a low price56/100$3/mocheapest paid plan - 4
mailbox.orgPeople who want to read their mail in Thunderbird or Outlook and switch on encryption themselves49/100$1.12/mocheapest paid plan - 5
Atomic MailPeople who want a free encrypted mailbox and apps on four systems47/100$5/mocheapest paid plan
Proton Mail vs Tuta Mail · Proton Mail vs Forward Email · All 9 encrypted email services
Sources
- Proton Mail pricing, Proton. Accessed 8 Oct 2026.
- Proton Mail encryption explained, Proton. Accessed 8 Oct 2026.
- Transparency report, Proton. Accessed 8 Oct 2026.
- Get Proton Mail apps, Proton. Accessed 8 Oct 2026.
- Open source and audits, Proton. Accessed 8 Oct 2026.
- ProtonMail/WebClients, GitHub. Accessed 8 Oct 2026.
- Two-factor authentication (2FA), Proton. Accessed 8 Oct 2026.
- Export emails with the Proton Mail Export Tool, Proton. Accessed 8 Oct 2026.
- Proton achieves ISO 27001 certification, Proton. Accessed 8 Oct 2026.
- Proton Calendar, Proton. Accessed 8 Oct 2026.
- Security audit, Proton. Accessed 8 Oct 2026.
- Install Proton Mail Bridge, Proton. Accessed 8 Oct 2026.
- Proton Mail desktop app, Proton. Accessed 8 Oct 2026.
Website: proton.me/mail · Markdown version · We are not affiliated with Proton AG.