Signal is the right answer for private conversations. Email is still the answer for receipts, contracts, password resets, and every business relationship that predates 2015. So the question is not whether to use encrypted email but which desktop client hurts your privacy the least. We looked at seven encrypted email apps that ship desktop builds for Windows, macOS, and Linux, and ranked them by what happens when you actually open a message.
What to look for in an encrypted email app
Email encryption is layered. A serious desktop client should handle most of these:
- At-rest encryption on the provider’s servers, so a subpoena or breach does not hand over readable mail.
- End-to-end encryption between provider accounts, ideally with automatic key exchange rather than manual PGP setup.
- Open PGP or S/MIME support for talking to people outside your provider.
- Zero-access architecture, meaning the provider cannot read your inbox even if compelled to.
- A jurisdiction you can live with, since data-request laws vary by country.
- A local desktop client, not a browser tab, so you can search and read offline.
Everything below meets at least four of those. The ranking below reflects which combinations actually work without you rebuilding your workflow.
Quick comparison
| App | Best for | Platforms | Free plan | Starting price/mo | Rating |
|---|---|---|---|---|---|
| Proton Mail | Overall privacy + polish | Win/Mac/Linux | 1 GB | $4.99 | 4.6 |
| Tuta | Free zero-access mail | Win/Mac/Linux | 1 GB | $3.60 | 4.5 |
| Mailfence | OpenPGP interop | Web/desktop bridge | 500 MB | $2.99 | 4.3 |
| Posteo | Anonymous signup | IMAP/POP + Thunderbird | No | $1.30 | 4.4 |
| Mailbox.org | Business features | IMAP + desktop client | No | $1.10 | 4.4 |
| StartMail | Aliases and disposables | Web + IMAP | 7-day trial | $2.92 | 4.2 |
| Thunderbird | Bring-your-own encryption | Win/Mac/Linux | Free | Free | 4.5 |
The apps
1. Proton Mail, best for overall privacy with a real desktop app
Proton Mail finally shipped a native desktop client for Windows, macOS, and Linux in 2024, ending years of “run it in a browser tab” complaints. Messages between Proton accounts are automatically end-to-end encrypted, and mail to outside PGP users works through published keys. The Swiss jurisdiction and zero-access architecture are the reasons this ranks first.
Where it falls short: The free tier is 1 GB, which fills quickly with attachments. Custom domain support requires a paid plan. Search is now full-text but only for the local cache, not server-side.
Pricing:
- Free: 1 GB, 150 messages per day, 1 address
- Paid: Mail Plus starts at $4.99/mo, unlocks 15 GB, custom domains, and unlimited folders
Platforms: Windows, macOS, Linux, iOS, Android
Download: Proton Mail for desktop
Bottom line: Best default pick for anyone who wants strong privacy defaults without configuring keys manually.
2. Tuta, best free zero-access mail
Tuta (formerly Tutanota) is German and uses its own encryption stack rather than PGP. Both message body and subject line are encrypted at rest, which sets it apart from most competitors that leave the subject in the clear. The desktop app is available for Windows, macOS, and Linux and supports offline reading.
Where it falls short: No IMAP or POP export, so switching providers later means using Tuta’s own export tool. Encryption to non-Tuta users happens through password-protected messages, which recipients open in a browser. Calendars and contacts work but lag on Proton’s polish.
Pricing:
- Free: 1 GB, 1 calendar, ad-free
- Paid: Revolutionary tier at $3.60/mo unlocks custom domains and 20 GB
Platforms: Windows, macOS, Linux, iOS, Android
Download: Tuta for desktop
Bottom line: Best free pick if you can live without IMAP and want subject-line encryption.
3. Mailfence, best for OpenPGP interop
Mailfence is Belgian and takes an interop-first approach. Instead of hiding PGP behind its own protocol, it exposes keys, signing, and verification through the standard OpenPGP model. That makes it the easiest option if you already exchange PGP mail with journalists, researchers, or open-source maintainers. Desktop use is through the web client plus IMAP/SMTP into Thunderbird or Apple Mail.
Where it falls short: No dedicated native desktop app. Free tier is 500 MB and no custom domains. Belgian data-retention rules apply, which some threat models rule out.
Pricing:
- Free: 500 MB, 1 calendar
- Paid: Entry plan starts at $2.99/mo, unlocks 10 GB and 5 custom domains
Platforms: Web, IMAP/SMTP to any desktop mail client
Download: Mailfence signup
Bottom line: Best pick if you actually send and receive PGP mail with people outside your provider.
4. Posteo, best for anonymous signup
Posteo is a Berlin-based provider that accepts anonymous cash payments through the mail and does not store personal metadata. There is no signup fee, no free tier, and no ads. Desktop access is standard IMAP/POP into Thunderbird, Apple Mail, or any client that speaks the protocol. Server-side encryption of the mailbox is opt-in.
Where it falls short: Anonymous payment sounds appealing but Posteo does not offer a free plan to test. No native mobile app; you use IMAP into whichever client you prefer. Server-side spam filtering happens before mailbox encryption, which is a documented trade-off.
Pricing:
- Free: none
- Paid: from about $1.30/mo (€1) for 2 GB, add-ons in €0.25 increments
Platforms: Web, IMAP/POP into any desktop client
Download: Posteo signup
Bottom line: Best pick when you want to pay anonymously with cash and use your existing desktop email client.
5. Mailbox.org, best for business features
Mailbox.org is another Berlin provider with a business focus. It bundles encrypted mail with a full office suite: calendar, contacts, tasks, files, and a document editor. Desktop use is IMAP/CalDAV/CardDAV into any standards-compliant client. PGP encryption is available server-side (Guard) and client-side.
Where it falls short: No native desktop app. The office suite has an early-2010s feel. Ad-hoc encryption to a non-PGP recipient requires a shared secret, which not every recipient will tolerate.
Pricing:
- Free: none
- Paid: Light tier at about $1.10/mo, Standard at $3.30/mo unlocks the full office suite
Platforms: Web, IMAP/CalDAV/CardDAV into any desktop client
Download: Mailbox.org signup
Bottom line: Best pick for a small team that needs mail, calendar, and files in one privacy-first bundle.
6. StartMail, best for aliases and disposable addresses
StartMail is Dutch, made by the same team behind Startpage. Its selling point is disposable aliases: create a fresh address per signup, disable it when the site starts spamming, and keep your main inbox clean. Desktop use is web plus IMAP/SMTP into Thunderbird.
Where it falls short: No native desktop app. Free tier is a 7-day trial only. PGP requires setup on both ends; no automatic key exchange between StartMail users.
Pricing:
- Free: 7-day trial
- Paid: Personal plan at $2.92/mo (billed annually) with unlimited aliases and 20 GB
Platforms: Web, IMAP/SMTP into any desktop client
Download: StartMail signup
Bottom line: Best pick if your privacy strategy revolves around alias management and disposable addresses.
7. Thunderbird with OpenPGP, best for bring-your-own encryption
Thunderbird is Mozilla’s open-source desktop mail client, and since version 78 it has shipped built-in OpenPGP support. You bring your own account (Fastmail, Posteo, Mailfence, even Gmail), generate a key, and Thunderbird handles the rest. The desktop app runs on Windows, macOS, and Linux with feature parity across platforms.
Where it falls short: Thunderbird itself is not an email provider, so the privacy of your inbox depends on the underlying account. Setting up PGP still means exchanging public keys the first time. UI updates have shipped in the last two years but still lag behind commercial clients.
Pricing:
- Free: entire client, all features, no ads
- Paid: none; Mozilla accepts donations
Platforms: Windows, macOS, Linux
Download: Thunderbird for desktop
Bottom line: Best pick if you already trust your email provider and want a free, open-source desktop client that handles PGP correctly.
How to pick the right one
- If you want the simplest option: Proton Mail. Sign up, install, encrypt by default.
- If you need PGP interop with strangers: Mailfence, or Thunderbird pointed at any account.
- If you refuse to pay: Tuta’s free tier is the best zero-cost option, followed by Thunderbird plus any free provider.
- If you want to pay anonymously: Posteo takes cash by mail. No other provider on this list does.
- If you tried Gmail’s “encrypted” mode and hated it: Any of the seven here. Gmail’s confidential mode does not encrypt against Google, only against forwarding.
- If you run a small team: Mailbox.org’s Standard plan gives you mail, calendar, files, and documents at one flat rate.
FAQ
What is the best free encrypted email desktop app?
Tuta is the strongest free option: 1 GB, subject-line encryption, no ads, and a native desktop app on Windows, macOS, and Linux. Proton Mail’s free tier is comparable but limits you to 150 outgoing messages per day.
Is Proton Mail worth paying for?
The $4.99/mo Mail Plus tier is the tier most people end up on. It removes the 150-message daily limit, adds custom domain support, and boosts storage to 15 GB. For a primary personal email account, it usually pays for itself in a couple of weeks.
Can I use my existing email address with an encrypted email app?
Only through Thunderbird plus OpenPGP, or Mailfence/Posteo/Mailbox.org via IMAP. Proton Mail and Tuta require an account on their own domain. Some providers offer custom-domain support on paid tiers so you can bring your own domain, though the mailbox itself still lives on their servers.
Does encrypted email still work with people on Gmail?
Yes, but only the parts you can encrypt end-to-end. Mail to Gmail from Proton or Tuta is encrypted in transit and at rest on your side, then delivered unencrypted to the Gmail inbox unless the recipient has a PGP key. Both providers support password-protected messages that Gmail users open in a browser, which restores end-to-end privacy for one-off communication.
Is IMAP compatible with encrypted email?
Yes for Mailfence, Posteo, Mailbox.org, and StartMail. Proton Mail requires the Proton Bridge, a small local app that translates between Proton’s protocol and IMAP so any desktop client can read Proton mail. Tuta does not offer IMAP as a design choice.
