--- title: Mozilla Thunderbird canonical: https://saasranked.com/software/mozilla-thunderbird/ category: Email Clients points: 88 rank: 1 of 10 facts_checked: 2026-10-08 --- # Mozilla Thunderbird Free, open-source email client for Windows, macOS, Linux and Android, with calendar, OpenPGP and S/MIME built in. 88 points out of 100. #1 of 10 email clients. Vendor: MZLA Technologies / Mozilla. Website: https://www.thunderbird.net/ - Thunderbird is free and funded by donations [1]. - Desktop apps run on Windows, macOS and Linux; a mobile app runs on Android [2]. - Native Exchange access arrived in version 145 (November 2025) over EWS; version 154 added Microsoft Graph, both for email only [6][9]. - OpenPGP, CalDAV and CardDAV appear in the 157.0 release notes, dated 30 September 2026; S/MIME appears in the 140.0 ESR notes [3][4]. - Mozilla says email is stored on your device and is not sent to Mozilla or Thunderbird servers [7]. Verdict: Thunderbird suits people who want a free client with a unified inbox, calendar and built-in OpenPGP and S/MIME [1][3][4]. Mail stays on your device, per its privacy policy [7]. The catch: Exchange access covers email only [6][9], and the vendor pages do not list snooze or undo send [1][3][5]. Best for: People who want a free, open-source client with built-in encryption. ## Points | Criterion | Line | Value | Points | Note | |---|---|---|---|---| | Mail and accounts | Account types | IMAP, POP3, Exchange, Gmail and Microsoft 365 sign-in | 12/12 | Release notes cover IMAP/POP setup and Gmail OAuth2; Exchange posts cover EWS, Graph and Microsoft OAuth2 sign-in [3][6][9]. | | Mail and accounts | Unified inbox | Yes | 4/4 | 'Manage all accounts separately or in a unified inbox' [1]. | | Mail and accounts | Mail tools | Scheduled send, Templates | 4/8 | Release notes refer to a 'Send Later' feature and to message templates. Snooze and undo send are not listed on pages read [5][10]. | | Mail and accounts | Filters and rules | Yes | 3/3 | Release notes describe message filters and the Quick Filter [4]. | | Calendar and contacts | Built-in calendar | Yes | 6/6 | Home page promises calendars in one app; release notes cover calendar setup and event fixes [1][4]. | | Calendar and contacts | CalDAV and CardDAV | Yes | 3/3 | Release notes mention CalDAV calendars and CardDAV address books syncing [3][4]. | | Privacy and encryption | OpenPGP | Yes | 7/7 | Release notes cover OpenPGP key import, discovery and encryption, built into the app [3][4]. | | Privacy and encryption | S/MIME | Yes | 6/6 | Release notes mention S/MIME signed-mail display and ECDH encryption and decryption; counted as built-in [4][5]. | | Privacy and encryption | Blocks tracking pixels | Not published | 0/4 | Not published on the vendor's pages [1][3]. | | Privacy and encryption | Open-source apps | Yes | 6/6 | Home page says Thunderbird is open source; the Android app is Apache-2.0 on GitHub [1][8]. | | Privacy and encryption | Mail stays on your device | Yes | 5/5 | Policy: messages are stored and processed locally; sync runs directly between Thunderbird and your provider [7]. | | Systems and upkeep | Other systems | macOS, Linux, Android | 6/10 | Download page lists desktop builds for macOS and Linux, and Android through Google Play and F-Droid [2]. | | Systems and upkeep | Released in the last year | Yes | 5/5 | Thunderbird 157.0 was released on September 30, 2026 [3]. | | Price | No ads in the app | Yes | 3/3 | Open-source app; the home page says it does not 'sell ads in your inbox' [1]. | | Price | Free plan | Yes | 6/6 | 'Free forever'; the full app is free [1]. | | Price | Cost of a year | $0 | 12/12 | The full app is free, funded by optional donations [1]. | ## Plans | Plan | Price | Per month (USD) | |---|---|---| | Thunderbird | Free [1] | $0 | ## Strengths - Free with no ads in the inbox, funded by donations [1]. - Mail is stored and processed on your device, not sent to Mozilla [7]. - Includes a unified inbox across accounts [1]. - Release notes show OpenPGP, S/MIME, CalDAV and CardDAV support [3][4]. ## Limits - Native Exchange access handles email only; calendar and address book are not yet available [6][9]. - No iOS app is listed on the download pages [2]. - Microsoft plans to switch off EWS on Microsoft 365 in phases from October 2026; Graph support is in the Release channel, not ESR 153 [9]. - Snooze and undo send are not listed on the vendor pages [1][3][5]. ## Vendor claims (not scored) - Thunderbird says it does not collect personal data or secretly train AI with private conversations [1]. ## Sources 1. [Thunderbird: Make Email Yours](https://www.thunderbird.net/en-US/), Thunderbird, accessed 2026-10-08 2. [Download Thunderbird: all platforms and languages](https://www.thunderbird.net/en-US/thunderbird/all/), Thunderbird, accessed 2026-10-08 3. [Thunderbird 157.0 release notes](https://www.thunderbird.net/en-US/thunderbird/157.0/releasenotes/), Thunderbird, accessed 2026-10-08 4. [Thunderbird 140.0esr release notes](https://www.thunderbird.net/en-US/thunderbird/140.0esr/releasenotes/), Thunderbird, accessed 2026-10-08 5. [Thunderbird 128.0esr release notes](https://www.thunderbird.net/en-US/thunderbird/128.0esr/releasenotes/), Thunderbird, accessed 2026-10-08 6. [Thunderbird adds native Microsoft Exchange email support](https://blog.thunderbird.net/2025/11/thunderbird-adds-native-microsoft-exchange-email-support/), Thunderbird Blog, accessed 2026-10-08 7. [Thunderbird privacy policy](https://www.thunderbird.net/en-US/privacy/), Thunderbird, accessed 2026-10-08 8. [thunderbird/thunderbird-android](https://github.com/thunderbird/thunderbird-android), GitHub, accessed 2026-10-08 9. [Thunderbird Desktop New Protocol Support: Microsoft Graph API](https://blog.thunderbird.net/2026/09/thunderbird-desktop-new-protocol-support-microsoft-graph-api/), Thunderbird Blog, accessed 2026-10-08 10. [Thunderbird 115.0esr release notes](https://www.thunderbird.net/en-US/thunderbird/115.0esr/releasenotes/), Mozilla Thunderbird, accessed 2026-10-08