16 rules in 5 groups, worth 100 points in all. They were set before any product was scored and apply the same way to all 9.
Version 1, published 8 Oct 2026
In short
Each rule is a yes-or-no fact, a list (such as the systems with an app) or a number with published thresholds, read from the vendor's own pages.
A fact the vendor does not publish earns nothing. A feature in beta or preview does not count.
The list follows the points. A tie goes to the lower price on "cheapest paid plan", then to the name.
Paid or free mailboxes for individuals whose vendor offers end-to-end or zero-access encryption. Used in a browser on Windows. Business email hosting, mainstream webmail and forwarding-only services are left out. "On at least one plan" counts only plans for individuals.
Encryption 27 points
Rule
What it takes
Points
Stored mail the provider cannot read
A vendor page documents that stored messages are encrypted with a key tied to your password (zero-access or end-to-end storage), so its staff cannot read them. It may be on by default or a setting you switch on, on at least one plan. Encryption that only protects the disks or the connection does not count.
10
Automatic end-to-end encryption between its own users
Mail between two accounts at the same service is end-to-end encrypted without the sender handling keys or passwords.
8
Encrypted mail to other providers
You can send an encrypted message to someone at another provider, using OpenPGP or a password-protected message, from the vendor's own mail interface.
6
Encrypted contacts or calendar
The vendor documents that the address book or the calendar is encrypted so the vendor cannot read it.
3
Trust and audits 26 points
Rule
What it takes
Points
Independent audit since 2024
A vendor page names an outside firm that audited or penetration-tested the product, and the report or a summary is published and dated 2024 or later. A general statement that the code was audited, with no firm named, does not count.
8
Open-source apps
The source code of the apps is public under an open-source licence.
6
SOC 2 Type II or ISO 27001
The vendor names a SOC 2 Type II report or an ISO/IEC 27001 certification for this product or the company running it.
4
Transparency report
The vendor publishes a count of legal requests it received, and the latest report covers a period ending in 2025 or later.
4
Security key for two-factor sign-in
You can protect the account with a FIDO2 or WebAuthn security key, such as a YubiKey, on at least one plan.
4
Apps and access 18 points
Rule
What it takes
Points
Official apps
An official desktop or mobile app from the vendor for each system (the web app and mail bridges do not count). Each one earns 2 points.
10
Works in standard mail programs
On at least one plan you can read the mailbox in a desktop mail program such as Thunderbird or Outlook, through IMAP and SMTP, or through a bridge app that the vendor itself publishes for that purpose (a paid-only bridge counts).
8
Mailbox 13 points
Rule
What it takes
Points
Your own domain
A plan for individuals lets you use an address on a domain you own.
5
Mail storage on the cheapest paid plan
Mail storage in gigabytes on the cheapest paid plan for one person. A shared pool for mail and files counts in full. 20 GB or more earns 5 points, 15 GB 4, 5 GB 3, 2 GB 2.
5
Export your whole mailbox
A help page describes a way to export all messages, with an export tool, a download or an IMAP copy that the vendor documents.
3
Price 16 points
Rule
What it takes
Points
Free plan with an encrypted mailbox
A free plan (not a trial) that lets you send and receive mail in a mailbox with the vendor's standard encryption. A free plan that only forwards mail does not count.
6
Cheapest paid plan
The cheapest paid plan for one person at its regular price (not a first-year offer), in US dollars a month before tax, on yearly billing where the vendor offers it and otherwise month by month. Prices shown in euros are converted. A product that is entirely free counts as $0. $1.50 or less earns 10 points, $3 or less 8, $4 or less 6, $5 or less 4, $7 or less 2.