# Mozilla Thunderbird vs Proton Mail

| Attribute | Mozilla Thunderbird | Proton Mail |
|---|---|---|
| **Vioscale score** | 60.1 (27% (low)) | 50.2 (76% (high)) |
| activity.commits_last_30d | 100 | - |
| adoption.dependent_repos | 0 | - |
| adoption.github_stars | 13,921 | - |
| deployment.options | - | `{"cloud":true}` |
| description.long | 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. | An email platform that uses end-to-end encryption to protect message contents from server access. Funded by subscribers rather than data exploitation, it provides privacy-focused communication for individuals and businesses with features like password-protected emails, alias generation, and team management tools. |
| features.capabilities | `{"pricing_model":"free_open_source","deployment_model":"local_direct_imap_client","generative_ai_llm_email_drafting":false,"unified_multi_account_inbox_view":true,"universal_imap_smtp_exchange_support":true}` | `{"iso_27001":true,"soc2_type_ii":false,"pricing_model":"freemium","deployment_model":"cloud_synchronization_proxy","conversational_chat_layout_view":false,"read_receipts_and_open_tracking":false,"snooze_and_scheduled_send_later":true,"generative_ai_llm_email_drafting":false,"unified_multi_account_inbox_view":true,"pgp_end_to_end_encryption_support":true,"split_inbox_ai_auto_categorization":false,"universal_imap_smtp_exchange_support":true,"keyboard_shortcut_only_navigation_speed":false}` |
| integrations.count | - | 11 |
| integrations.list | - | `[{"name":"Gmail"},{"name":"Outlook"},{"name":"Yahoo"},{"name":"Apple Mail"},{"name":"Thunderbird"},{"name":"Google"},{"name":"Okta"},{"name":"Microsoft Entra ID"},{"name":"ADFS"},{"name":"Edugain"},{"name":"SimpleLogin"}]` |
| language.primary | Kotlin | - |
| license.spdx | Apache-2.0 | - |
| market.availability | - | `{"hqCountry":"CH","primaryMarkets":["EU","US","GB"],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]}` |
| platform.support | `{"mac":true,"linux":true,"windows":true}` | `{"cli":true,"ios":true,"mac":true,"web":true,"linux":true,"android":true,"windows":true}` |
| pricing | `{"type":"free","summary":"Free, open-source. Free forever.","freeTier":true,"sourceUrl":"https://www.thunderbird.net","retrievedAt":"2026-08-21T12:42:28.376Z"}` | `{"type":"freemium","plans":[{"free":false,"name":"Essential","features":["Unlimited logins, notes, and credit cards","Browser, mobile, and desktop apps","Secure vault, item and link sharing","Built-in 2FA authenticator","Dark Web Monitoring","Passkey support on all devices","Unlimited hide-my-email aliases"],"description":"Account protection for small teams","contactSales":false,"includedLimits":{"notes":"unlimited","logins":"unlimited","credit_cards":"unlimited","hide_my_email_aliases":"unlimited"}},{"free":false,"name":"Plus","features":["SSO and SCIM","Access to Proton Sentinel","File storage up to 100 MB","SIEM integration","Command line interface (CLI)","Group management for organizing users"],"description":"Advanced account protection with admin controls","contactSales":false,"includedLimits":{"file_storage":"100 MB"}},{"free":false,"name":"Workspace Standard","features":["1 TB storage per user","15 custom email domains","Secure personal and shared calendar","Cloud storage and sharing","User permissions and access management","VPN connection for 10 devices per user"],"description":"Password manager with storage and team collaboration","contactSales":false,"includedLimits":{"vpn_devices":"10","storage_per_user":"1 TB","custom_email_domains":"15"}}],"addOns":[{"name":"Dedicated server and IP"}],"currency":"USD","freeTier":true,"sourceUrl":"https://proton.me/business/pass/pricing","retrievedAt":"2026-08-25T12:07:33.063Z","freeTrialDays":14,"billingPeriods":["month","year"]}` |
| pricing.free_tier | yes | yes |
| pricing.model | freemium | freemium |
| pricing.price_level | free | low |
| pricing.transparent | yes | no |
| release.history | `[{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_22_0","date":"2026-08-11T03:59:18Z","type":"stable","version":"THUNDERBIRD_22_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_22_0","date":"2026-08-11T03:59:18Z","type":"stable","version":"K9MAIL_22_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_23_0b1","date":"2026-08-10T22:13:14Z","type":"prerelease","version":"THUNDERBIRD_23_0b1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_1","date":"2026-08-03T19:14:04Z","type":"stable","version":"THUNDERBIRD_21_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_21_1","date":"2026-08-03T19:14:10Z","type":"stable","version":"K9MAIL_21_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_22_0b2","date":"2026-07-27T20:45:48Z","type":"prerelease","version":"THUNDERBIRD_22_0b2"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_0","date":"2026-07-20T21:30:00Z","type":"stable","version":"THUNDERBIRD_21_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_21_0","date":"2026-07-20T21:29:55Z","type":"stable","version":"K9MAIL_21_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_22_0b1","date":"2026-07-20T23:20:30Z","type":"prerelease","version":"THUNDERBIRD_22_0b1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_20_1","date":"2026-07-06T22:30:54Z","type":"stable","version":"THUNDERBIRD_20_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_20_1","date":"2026-07-06T22:30:53Z","type":"stable","version":"K9MAIL_20_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_0b2","date":"2026-06-29T21:12:45Z","type":"prerelease","version":"THUNDERBIRD_21_0b2"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_20_0","date":"2026-06-23T01:45:10Z","type":"stable","version":"K9MAIL_20_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_20_0","date":"2026-06-23T01:45:03Z","type":"stable","version":"THUNDERBIRD_20_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_21_0b1","date":"2026-06-22T17:24:23Z","type":"prerelease","version":"THUNDERBIRD_21_0b1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_19_2","date":"2026-06-04T19:32:37Z","type":"stable","version":"THUNDERBIRD_19_2"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_19_2","date":"2026-06-04T19:32:32Z","type":"stable","version":"K9MAIL_19_2"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_20_0b2","date":"2026-06-04T18:27:10Z","type":"prerelease","version":"THUNDERBIRD_20_0b2"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_19_1","date":"2026-06-03T22:11:56Z","type":"stable","version":"THUNDERBIRD_19_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_19_1","date":"2026-06-03T22:11:55Z","type":"stable","version":"K9MAIL_19_1"}]` | - |
| reliability.sla_pct | - | 99.95 |
| security.gdpr | - | yes |
| security.hipaa | - | yes |
| security.iso27001 | - | yes |
| security.pci | - | yes |
| security.scorecard | 7.2 | - |
| 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}` | - |

## Capabilities (Email Clients)

| Capability | Mozilla Thunderbird | Proton Mail |
|---|:--:|:--:|
| **Capabilities** |  |  |
| Deployment model | Local direct imap client | Cloud synchronization proxy |
| 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 | Freemium |

*Source: Vioscale. Generated 2026-09-01T16:48:11.899Z. "-" = undocumented, not absent.*