# Mozilla Thunderbird

- **Canonical URI:** https://www.vioscale.ai/software/mozilla-thunderbird
- **Category:** Email Clients
- **Homepage:** https://www.thunderbird.net
- **Also known as:** mozilla-thunderbird
- **Profile claimed by vendor:** no
- **Last updated:** 2026-08-26T19:18:55.950Z

## Vioscale score

**60.1 / 100**, confidence 27% (low). Computed 2026-09-01.

Composite of weighted, independently-sourced signals (no user reviews, no vendor payment).

| Signal | Score | Weight | Contribution | Evidence present |
|---|--:|--:|--:|:--:|
| price_level | 100 | 0.052 | 5.2 | ✓ |
| reliability | 0 | 0.073 | 0 | - |
| capabilities | 45.8 | 0.084 | 3.8 | ✓ |
| repo_stars | 78.2 | 0.026 | 2 | ✓ |
| integrations | 0 | 0.09355555555555557 | 0 | - |
| dependent_projects | 0 | 0.063 | 0 | ✓ |
| dev_activity | 63.1 | 0.094 | 5.9 | ✓ |
| release_cadence | 0 | 0.052 | 0 | - |
| security_posture | 0 | 0.073 | 0 | - |
| package_downloads | 0 | 0.136 | 0 | - |
| security_score | 72 | 0.042 | 3 | ✓ |
| pricing_transparency | 80 | 0.084 | 6.7 | ✓ |
| community_qa_activity | 0 | 0.063 | 0 | - |

## Pricing

_As of 2026-08-21, [verify at source](https://www.thunderbird.net). Independently observed._

Free · Free tier

> Free, open-source. Free forever.

## About

Thunderbird consolidates email, calendars, and contacts from multiple accounts into one interface. It runs on Windows, Mac, and Linux, is funded by user donations, and prioritizes privacy by never collecting personal data or serving advertisements.

_Independently observed._

## Platform & deployment

- **Platforms:** macOS, Linux, Windows

## Capabilities

_The capabilities that matter for Email Clients. "-" = undocumented, not absent._

| Capability | Supported |
|---|:--:|
| **Capabilities** | |
| Deployment model | Local direct imap client |
| Universal imap smtp exchange support | ✓ |
| Keyboard shortcut only navigation speed | - |
| Split inbox AI auto categorization | - |
| Read receipts and open tracking | - |
| Snooze and scheduled send later | - |
| Generative AI LLM email drafting | ✗ |
| Conversational chat layout view | - |
| Unified multi account inbox view | ✓ |
| Pgp end to end encryption support | - |
| SOC2 type ii | - |
| ISO 27001 | - |
| Pricing model | Free open source |

## Release history

| Version | Date | Type |
|---|---|---|
| [THUNDERBIRD_22_0](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_22_0) | 2026-08-11 | stable |
| [K9MAIL_22_0](https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_22_0) | 2026-08-11 | stable |
| [THUNDERBIRD_23_0b1](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_23_0b1) | 2026-08-10 | prerelease |
| [THUNDERBIRD_21_1](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_1) | 2026-08-03 | stable |
| [K9MAIL_21_1](https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_21_1) | 2026-08-03 | stable |
| [THUNDERBIRD_22_0b2](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_22_0b2) | 2026-07-27 | prerelease |
| [THUNDERBIRD_21_0](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_0) | 2026-07-20 | stable |
| [K9MAIL_21_0](https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_21_0) | 2026-07-20 | stable |
| [THUNDERBIRD_22_0b1](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_22_0b1) | 2026-07-20 | prerelease |
| [THUNDERBIRD_20_1](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_20_1) | 2026-07-06 | stable |
| [K9MAIL_20_1](https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_20_1) | 2026-07-06 | stable |
| [THUNDERBIRD_21_0b2](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_0b2) | 2026-06-29 | prerelease |
| [K9MAIL_20_0](https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_20_0) | 2026-06-23 | stable |
| [THUNDERBIRD_20_0](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_20_0) | 2026-06-23 | stable |
| [THUNDERBIRD_21_0b1](https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_0b1) | 2026-06-22 | prerelease |

_… and 5 earlier release(s)._

## Security & compliance


Known vulnerabilities: 0 (0 in the last 12 months) ([source](https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=fdroid&package_name=com.fsck.k9&per_page=100)). A count reflects scale and disclosure, not quality.

## Facts

Every value below carries its source and our confidence. Facts are re-crawled on a freshness schedule.

### pricing

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| pricing.model | freemium | [link](https://www.thunderbird.net) | 2026-08-26 | 56% (medium) |
| pricing.free_tier | yes | [link](https://www.thunderbird.net) | 2026-08-26 | 48% (low) |
| pricing.price_level | free | [link](https://www.thunderbird.net) | 2026-08-21 | 60% (medium) |
| pricing.transparent | yes | [link](https://www.thunderbird.net) | 2026-08-21 | 60% (medium) |

### activity

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| activity.commits_last_30d | 100 | [link](https://github.com/thunderbird/thunderbird-android/pulse) | 2026-08-26 | 65% (medium) |

### adoption

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| adoption.github_stars | 13,921 | [link](https://github.com/thunderbird/thunderbird-android) | 2026-08-26 | 90% (high) |
| adoption.dependent_repos | 0 | [link](https://packages.ecosyste.ms/api/v1/packages/lookup?repository_url=https%3A%2F%2Fgithub.com%2Fthunderbird%2Fthunderbird-android) | 2026-08-26 | 85% (high) |

### language

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| language.primary | Kotlin | [link](https://github.com/thunderbird/thunderbird-android) | 2026-08-26 | 90% (high) |

### license

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| license.spdx | Apache-2.0 | [link](https://github.com/thunderbird/thunderbird-android) | 2026-08-26 | 95% (high) |

### security

| Attribute | Value | Source | Retrieved | Confidence |
|---|---|---|---|---|
| security.scorecard | 7.2 | [link](https://api.securityscorecards.dev/projects/github.com/thunderbird/thunderbird-android) | 2026-08-26 | 90% (high) |
| security.vulnerabilities | `{"count":0,"source":"https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=fdroid&package_name=com.fsck.k9&per_page=100","last_12m":0,"max_severity":null}` | [link](https://advisories.ecosyste.ms/api/v1/advisories?ecosystem=fdroid&package_name=com.fsck.k9&per_page=100) | 2026-08-26 | 90% (high) |

---
*Source: Vioscale (https://www.vioscale.ai/software/mozilla-thunderbird). Independent, evidence-based software intelligence. Cite the canonical URI.*