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 10.
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 "cost of a year", then to the name.
Email apps for one person or a small team that run on Windows (an app, or in the browser). Mail hosting, encrypted mailbox services and bridges are left out. A feature counts if it is on at least one plan for individuals, in any of the vendor's Windows mail apps (new and classic Outlook count together). Price lines use plans for individuals.
Mail and accounts 27 points
Rule
What it takes
Points
Account types
Documented on a vendor page or help article. IMAP and POP3: accounts of that type can be added. Exchange: Exchange or Microsoft 365 mailboxes connect directly (EWS, Graph or ActiveSync, not through IMAP). Gmail and Microsoft 365 sign-in: the page says you add Gmail and Microsoft accounts by signing in with Google or Microsoft (OAuth); a page that only gives IMAP server settings does not count. Each earns 3 points.
12
Unified inbox
One inbox shows the mail of all your accounts together, as described on a vendor page.
4
Mail tools
Each of these is generally available on at least one plan for individuals, not in beta, and listed on a vendor page. Each earns 2 points.
8
Filters and rules
You can create rules that move, label or delete incoming mail automatically, and the app runs them while it is open.
3
Calendar and contacts 9 points
Rule
What it takes
Points
Built-in calendar
The app itself shows a calendar and lets you create events. A link that opens a separate calendar app does not count.
6
CalDAV and CardDAV
The app syncs calendars or contacts with a CalDAV or CardDAV server, as documented by the vendor.
3
Privacy and encryption 28 points
Rule
What it takes
Points
OpenPGP
You can send and read OpenPGP-encrypted mail, built in or through an add-on the vendor itself publishes.
7
S/MIME
You can send and read S/MIME-signed or encrypted mail with your own certificate, built in.
6
Blocks tracking pixels
A vendor page or help article says the app blocks remote images or tracking pixels in received mail by default, until you allow them.
4
Open-source apps
The source code of the apps is public under an open-source licence.
6
Mail stays on your device
The vendor's privacy policy or help pages state in words that mail is fetched directly from your provider to the app, and is not stored on or passed through the vendor's servers. Silence, or a page that only describes encryption, is null.
5
Systems and upkeep 15 points
Rule
What it takes
Points
Other systems
An official app from the vendor for each system, or a web app. Each earns 2 points. Windows is a condition for being listed and earns nothing.
10
Released in the last year
The vendor's release notes, changelog or download page show a dated release of the Windows app within 12 months before the research date.
5
Price 21 points
Rule
What it takes
Points
No ads in the app
True if the plan used for the price line is a paid plan or licence, or the app is open-source, or a vendor page says the app has no ads. False if a vendor page says or shows that the plan displays advertising inside the app (for example a free tier funded by ads).
3
Free plan
A free plan or free version for personal use, with no time limit, lets you send and receive mail from at least one account. A free trial does not count.
6
Cost of a year
Cost of 12 months for one person on the cheapest plan for individuals with no limit on the number of mail accounts, at the regular price (not a launch or seasonal offer) before tax: the yearly price, 12 times the monthly price, or the full price of a one-time licence, whichever is lowest. Add-on subscriptions for AI do not count. A free plan with an account limit does not count; a product whose full app is free counts as $0.