# Mozilla Thunderbird vs Proton Mail

**Leader by vioscaleAI score:** Proton Mail

| Attribute | Mozilla Thunderbird | Proton Mail |
|---|---|---|
| **vioscaleAI score** | 48.7 (44% (low)) | 75 (72% (medium)) |
| activity.commits_last_30d | 100 | - |
| adoption.dependent_repos | 0 | - |
| adoption.github_stars | 14,107 | - |
| content.faq | `[{"answer":"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. It is indexed under Email Clients.","source":"https://www.thunderbird.net","question":"What is Mozilla Thunderbird?","confidence":0.6},{"answer":"Mozilla Thunderbird offers a free tier, so you can start without paying. Pricing changes often, so verify at source before relying on it.","source":"https://www.thunderbird.net","question":"Is Mozilla Thunderbird free?","confidence":0.6},{"answer":"Mozilla Thunderbird supports Windows, macOS and Linux. Platforms we have not confirmed are simply not listed here rather than ruled out.","source":"https://www.thunderbird.net","question":"What platforms does Mozilla Thunderbird support?","confidence":0.6},{"answer":"Yes. Mozilla Thunderbird is published under the Apache-2.0 licence, a permissive licence that generally allows commercial use and modification. Licence terms can change between releases, so verify against the repository for the version you intend to use.","source":"https://github.com/thunderbird/thunderbird-android","question":"Is Mozilla Thunderbird open source?","confidence":0.95}]` | `[{"answer":"An email platform using zero-access encryption so the provider cannot read messages, funded by subscriptions rather than data exploitation. It is indexed under Email Clients.","source":"https://proton.me/business/pass/pricing","question":"What is Proton Mail?","confidence":0.6},{"answer":"Proton Mail offers a free tier, so you can start without paying. Paid plans are also available: Pass Essentials, Pass Professional, VPN and Pass Professional and Workspace Standard. Pricing changes often, so verify at source before relying on it.","source":"https://proton.me/business/pass/pricing","question":"Is Proton Mail free?","confidence":0.6},{"answer":"Proton Mail supports the web, Windows, macOS, Linux, iOS, Android and a command-line interface. Platforms we have not confirmed are simply not listed here rather than ruled out.","source":"https://proton.me/business/pass/pricing","question":"What platforms does Proton Mail support?","confidence":0.6},{"answer":"We have only confirmed a cloud / SaaS deployment for Proton Mail, so it appears to be vendor-hosted. If a self-hosted option exists we have not found it documented publicly.","source":"https://proton.me/business/pass/pricing","question":"Can Proton Mail be self-hosted?","confidence":0.6},{"answer":"We have confirmed 11 integrations for Proton Mail, including Gmail, Outlook, Yahoo, Apple Mail, Thunderbird, Google, Okta and Microsoft Entra ID, plus 3 more. This is what we could verify from public sources, so the vendor may support others we have not indexed.","source":"https://proton.me/business/pass/pricing","question":"What does Proton Mail integrate with?","confidence":0.6},{"answer":"We have independently confirmed SOC 2, ISO 27001, HIPAA and GDPR for Proton Mail. Certifications we do not list are ones we have not been able to verify from public sources, which is not the same as Proton Mail not holding them. Always confirm compliance directly before you rely on it.","source":"https://proton.me/nb/business/mail/security","question":"What security certifications does Proton Mail have?","confidence":0.7},{"answer":"Proton Mail is available worldwide. Its primary markets are the EU, the United States and the United Kingdom. The vendor is headquartered in Switzerland.","source":"https://proton.me/business/pass/pricing","question":"Where is Proton Mail available?","confidence":0.75}]` |
| 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. | A cloud-based email platform using end-to-end encryption to keep all messages private from Proton and advertisers, funded by subscriber revenue. It provides a permanent free tier with core email functionality, plus paid plans offering enhanced storage, custom domains, and integrated business services. |
| 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":true,"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":true,"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 | - | 7 |
| 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"},{"name":"Yahoo Mail","native":false,"category":"email","direction":"inbound"},{"name":"Chrome","native":false,"direction":"bidirectional"},{"name":"Firefox","native":false,"direction":"bidirectional"}]` |
| language.primary | Kotlin | - |
| license.spdx | Apache-2.0 | - |
| market.availability | - | `{"primaryMarkets":[],"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":true,"name":"Free","summary":"Free forever","features":["End-to-end encryption","Email and calendar access"],"components":[{"kind":"fixed","amount":0,"period":"month","currency":"USD"}],"description":"Basic email functionality with the same encryption and security as paid plans","contactSales":false},{"free":false,"name":"Workspace Standard","summary":"$12.99/user/month, billed annually at $155.88","features":["1 TB cloud storage","15 custom email domains","VPN access for 10 devices","25 booking pages","Password manager","Collaborative document editing"],"commitment":"annual","components":[{"kind":"fixed","amount":12.99,"period":"month","currency":"USD"}],"description":"All Proton products bundled including email, storage, VPN, and collaboration tools for teams","contactSales":false,"includedLimits":{"storage":"1 TB per user","calendars":"25","custom_domains":"15"}}],"summary":"Free tier available. Paid plans starting at $12.99/user/month for business bundles.","currency":"USD","freeTier":true,"sourceUrl":"https://proton.me/business/pass/pricing","retrievedAt":"2026-10-12T16:05:55.600Z","startingPrice":{"amount":12.99,"period":"month","currency":"USD"},"billingPeriods":["month","year"]}` |
| pricing.free_tier | yes | yes |
| pricing.model | freemium | freemium |
| pricing.price_level | free | low |
| pricing.starting_price | - | `{"amount":12.99,"currency":"USD"}` |
| pricing.transparent | yes | yes |
| release.history | `[{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_24_0","date":"2026-10-05T23:38:09Z","type":"stable","version":"THUNDERBIRD_24_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_24_0","date":"2026-10-05T23:38:15Z","type":"stable","version":"K9MAIL_24_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_25_0b1","date":"2026-10-05T23:36:57Z","type":"prerelease","version":"THUNDERBIRD_25_0b1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_23_1","date":"2026-09-22T05:59:49Z","type":"stable","version":"THUNDERBIRD_23_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_23_1","date":"2026-09-22T05:59:50Z","type":"stable","version":"K9MAIL_23_1"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_24_0b2","date":"2026-09-14T18:09:35Z","type":"prerelease","version":"THUNDERBIRD_24_0b2"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_23_0","date":"2026-09-09T06:41:45Z","type":"stable","version":"THUNDERBIRD_23_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/K9MAIL_23_0","date":"2026-09-09T06:41:39Z","type":"stable","version":"K9MAIL_23_0"},{"url":"https://github.com/thunderbird/thunderbird-android/releases/tag/THUNDERBIRD_24_0b1","date":"2026-09-08T22:28:10Z","type":"prerelease","version":"THUNDERBIRD_24_0b1"},{"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"}]` | - |
| reliability.sla_pct | - | 99.95 |
| security.certifications | - | `[{"name":"ISO 27001","status":"active"}]` |
| security.gdpr | - | yes |
| security.hipaa | - | yes |
| security.iso27001 | - | yes |
| security.pci | - | yes |
| security.scorecard | 7.2 | - |
| security.soc2 | - | yes |
| security.trust_center | - | https://proton.me/nb/business/mail/security |
| 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: vioscaleAI. Generated 2026-10-16T20:14:50.384Z. "-" = undocumented, not absent.*