Private and open-source alternatives to Microsoft Outlook
15 email clients rated against the same public privacy criteria as Microsoft Outlook (Outlook app, new Outlook for Windows), with our picks first.
Why look for an alternative?
- Open source: no. Closed source.
- No trackers or telemetry: no. Exodus finds six trackers in the Android app, including AppNexus, Facebook Ads and Singular.
- No ads or data sales: no. The free Outlook apps show ads to users without a paid Microsoft 365 plan.
- Independent audit: no. No independent audit of the Outlook apps is published.
- OpenPGP support: no. Not supported. S/MIME and Microsoft Purview encryption are available instead.
- Connects directly: no. The mobile app syncs mail from all added accounts, including third-party ones, to Microsoft servers. Desktop sync to Microsoft servers is optional.
- Blocks remote content: partial. Classic Outlook for Windows blocks automatic picture downloads by default. Other Outlook apps differ.
See the full Microsoft Outlook rating.
The alternatives
Forward Email Grade B Our pick
Email client for Forward Email accounts, available as webmail and as desktop and mobile apps built from one source-available codebase, with built-in OpenPGP and optional encryption of locally stored data.
Why it is our pick: Source-available webmail, desktop and mobile client with built-in OpenPGP and no third-party analytics. It works only with Forward Email accounts, not other IMAP and SMTP providers.
Based in the United States (Five Eyes). Forward Email scores 81 out of 100 (grade B) on the email clients criteria. It meets 5 of 8 criteria: open source, no ads or data sales, independent audit, OpenPGP support and connects directly.
Betterbird Grade B Our pick
Fork of Mozilla Thunderbird that follows its Extended Support Releases and adds extra fixes and features. Available for Windows, macOS and Linux.
Why it is our pick: Open-source (MPL-2.0) fork of Thunderbird with telemetry reporting turned off and built-in OpenPGP and S/MIME. It connects directly to any IMAP, POP3 and SMTP provider and blocks remote content by default.
Based in Germany (Fourteen Eyes). Betterbird scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
Delta Chat Grade A
Decentralized messenger that uses email servers for delivery, with automatic end-to-end encryption through Autocrypt and OpenPGP. Works with chatmail relays or existing email accounts.
Based in Germany (Fourteen Eyes). Delta Chat scores 92 out of 100 (grade A) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, independent audit, OpenPGP support, blocks remote content and works with any provider.
aerc Grade B
Terminal email client for Linux and macOS with IMAP, JMAP, Maildir and Notmuch support and PGP encryption through GnuPG.
aerc scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
Claws Mail Grade B
Lightweight GTK email and news client for Linux and Windows, extended through plugins for OpenPGP, HTML rendering and spam filtering.
Claws Mail scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
Evolution Grade B
GNOME groupware application for Linux that combines email, calendar, contacts and tasks, with support for IMAP, POP3, Exchange and OpenPGP.
Based in the United States (Five Eyes). Evolution scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
KMail Grade B
KDE email client for Linux, part of the Kontact suite, with support for IMAP, POP3, OpenPGP and S/MIME.
Based in Germany (Fourteen Eyes). KMail scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
Mutt Grade B
Text-based terminal email client for Unix-like systems with built-in IMAP, POP3 and SMTP support, message threading and OpenPGP and S/MIME encryption.
Mutt scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
NeoMutt Grade B
Terminal email client for Linux and macOS based on Mutt, with built-in IMAP, POP3, SMTP and OpenPGP support.
NeoMutt scores 89 out of 100 (grade B) on the email clients criteria. It meets 7 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
Thunderbird for Android Grade B
Open-source email app for Android from the Thunderbird project, based on K-9 Mail, which remains available as a variant. Works with any IMAP, POP3 and SMTP provider.
Based in the United States (Five Eyes). Thunderbird for Android scores 89 out of 100 (grade B) on the email clients criteria. It meets 6 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, connects directly, blocks remote content and works with any provider.
Mozilla Thunderbird Grade B
Open-source desktop email client for Windows, macOS and Linux with calendar, contacts and built-in OpenPGP and S/MIME encryption.
Based in the United States (Five Eyes). Mozilla Thunderbird scores 86 out of 100 (grade B) on the email clients criteria. It meets 6 of 8 criteria: open source, no ads or data sales, OpenPGP support, connects directly, blocks remote content and works with any provider.
Alpine Grade B
Text-based email client derived from Pine, for Unix-like systems and Windows, with built-in IMAP, POP3 and SMTP support and S/MIME encryption.
Alpine scores 83 out of 100 (grade B) on the email clients criteria. It meets 6 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, connects directly, blocks remote content and works with any provider.
FairEmail Grade B
Open-source email app for Android that works with any IMAP, POP3 and SMTP provider and supports multiple accounts with a unified inbox.
FairEmail scores 83 out of 100 (grade B) on the email clients criteria. It meets 6 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, connects directly, blocks remote content and works with any provider.
Himalaya Grade B
Command-line email client that manages mail over IMAP, JMAP, SMTP, Maildir, the Gmail API and Microsoft Graph, with composing and reading handled by the companion MML tool.
Himalaya scores 83 out of 100 (grade B) on the email clients criteria. It meets 6 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, connects directly, blocks remote content and works with any provider.
Geary Grade B
Email app for the GNOME desktop on Linux that groups messages into conversations and works with IMAP accounts.
Based in the United States (Five Eyes). Geary scores 78 out of 100 (grade B) on the email clients criteria. It meets 6 of 8 criteria: open source, no trackers or telemetry, no ads or data sales, connects directly, blocks remote content and works with any provider.