{
  "slug": "mozilla-thunderbird",
  "category": "email-clients",
  "name": "Mozilla Thunderbird",
  "description": "Open-source desktop email client for Windows, macOS and Linux with calendar, contacts and built-in OpenPGP and S/MIME encryption.",
  "website": "https://www.thunderbird.net",
  "source": "https://github.com/mozilla/releases-comm-central",
  "license": null,
  "platforms": [],
  "jurisdiction": {
    "code": "US",
    "name": "United States",
    "eyes": "Five Eyes",
    "eu": false,
    "gdpr": false,
    "cloud_act": "provider"
  },
  "pick": false,
  "pick_reason": null,
  "disclosure": null,
  "grade": "B",
  "score": 86,
  "coverage": 100,
  "summary": "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. It partly meets no trackers or telemetry and independent audit. It is based in the United States: Five Eyes member; subject to the US CLOUD Act.",
  "url": "https://privacyratings.com/email-clients/mozilla-thunderbird/",
  "markdown": "https://privacyratings.com/email-clients/mozilla-thunderbird/index.md",
  "answers": {
    "open_source": {
      "title": "Open source",
      "weight": 3,
      "answer": "yes",
      "evidence": "https://www.mozilla.org/en-US/MPL/2.0/",
      "note": "MPL-2.0."
    },
    "no_trackers": {
      "title": "No trackers or telemetry",
      "weight": 3,
      "answer": "partial",
      "evidence": "https://support.mozilla.org/en-US/kb/thunderbird-telemetry",
      "note": "Sends first-party telemetry to Mozilla by default, which can be turned off in settings."
    },
    "no_ads": {
      "title": "No ads or data sales",
      "weight": 2,
      "answer": "yes",
      "evidence": "https://www.thunderbird.net/en-US/donate/",
      "note": "Funded by user donations. No ads."
    },
    "independent_audit": {
      "title": "Independent audit",
      "weight": 2,
      "answer": "partial",
      "evidence": "https://posteo.de/en/blog/security-warning-for-thunderbird-users-and-enigmail-users-vulnerabilities-threaten-confidentiality-of-communication",
      "note": "Cure53 audited Thunderbird and Enigmail, but only a summary is public and the audit is more than three years old."
    },
    "transparency_report": {
      "title": "Transparency report",
      "weight": 2,
      "answer": "n/a",
      "evidence": null,
      "note": "Only applies to hosted services with a website to test."
    },
    "user_notice": {
      "title": "Tells users about requests",
      "weight": 1,
      "answer": "n/a",
      "evidence": null,
      "note": "Only applies to hosted services with a website to test."
    },
    "tls": {
      "title": "TLS configuration",
      "weight": 2,
      "answer": "n/a",
      "evidence": null,
      "note": "Only applies to hosted services with a website to test."
    },
    "security_headers": {
      "title": "Security headers",
      "weight": 1,
      "answer": "n/a",
      "evidence": null,
      "note": "Only applies to hosted services with a website to test."
    },
    "web_standards": {
      "title": "Modern web standards",
      "weight": 1,
      "answer": "n/a",
      "evidence": null,
      "note": "Only applies to hosted services with a website to test."
    },
    "openpgp": {
      "title": "OpenPGP support",
      "weight": 2,
      "answer": "yes",
      "evidence": "https://support.mozilla.org/en-US/kb/openpgp-thunderbird-howto-and-faq",
      "note": "OpenPGP and S/MIME are built in."
    },
    "no_cloud_relay": {
      "title": "Connects directly",
      "weight": 3,
      "answer": "yes",
      "evidence": "https://www.mozilla.org/en-US/privacy/thunderbird/",
      "note": "Connects directly to mail servers. Mail, contacts and account details stay on the device."
    },
    "remote_content_blocked": {
      "title": "Blocks remote content",
      "weight": 2,
      "answer": "yes",
      "evidence": "https://support.mozilla.org/en-US/kb/remote-content-in-messages",
      "note": "Remote content is blocked by default."
    },
    "any_provider": {
      "title": "Works with any provider",
      "weight": 1,
      "answer": "yes",
      "evidence": "https://support.mozilla.org/en-US/kb/manual-account-configuration",
      "note": "Works with any IMAP, POP3 and SMTP provider."
    }
  },
  "tests": {
    "ssllabs": null,
    "observatory": null,
    "internetnl_web": null,
    "internetnl_mail": null,
    "trackers": [],
    "tested_at": "2026-10-01T07:01:51.432Z"
  },
  "last_modified": "2026-10-01T07:44:20Z"
}