# Mailspring vs Mozilla Thunderbird

**Leader by vioscaleAI score:** Mailspring

| Attribute | Mailspring | Mozilla Thunderbird |
|---|---|---|
| **vioscaleAI score** | 58.5 (65% (medium)) | 48.7 (44% (low)) |
| activity.commits_last_30d | 100 | 100 |
| adoption.dependent_repos | - | 0 |
| adoption.github_stars | 17,885 | 14,107 |
| content.faq | `[{"answer":"A lightweight desktop application for Mac, Windows, and Linux that brings together multiple email accounts from different providers into one unified inbox. Core features run locally on your computer, with optional paid features for message tracking, scheduling, and productivity analytics. It is indexed under Email Clients.","source":"https://getmailspring.com","question":"What is Mailspring?","confidence":0.6},{"answer":"Mailspring is open source, so it can be self-hosted and used at no licence cost. It is released under the GPL-3.0 licence. A commercial or hosted edition starts at $8 per month. Prices are published openly on the vendor's own pricing page. Pricing changes often, so verify at source before relying on it.","source":"https://getmailspring.com","question":"Is Mailspring free to use?","confidence":0.6},{"answer":"Mailspring supports Windows, macOS and Linux. Platforms we have not confirmed are simply not listed here rather than ruled out.","source":"https://getmailspring.com","question":"What platforms does Mailspring support?","confidence":0.6},{"answer":"We have confirmed 8 integrations for Mailspring, including Gmail, iCloud, Office 365, FastMail, Outlook.com, Yahoo!, IMAP and SMTP. This is what we could verify from public sources, so the vendor may support others we have not indexed.","source":"https://getmailspring.com","question":"What does Mailspring integrate with?","confidence":0.6},{"answer":"Yes. Mailspring is published under the GPL-3.0 licence, a copyleft licence, so check its terms before embedding it in a closed-source product. Licence terms can change between releases, so verify against the repository for the version you intend to use.","source":"https://github.com/foundry376/Mailspring","question":"Is Mailspring open source?","confidence":0.95}]` | `[{"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}]` |
| deployment.options | `{"self_hosted":true}` | - |
| description.long | Mailspring is a desktop email client built as open source that runs your sync engine locally without sending credentials to remote servers. It includes core features like unified inbox, snooze, scheduled sending, and mail rules, with optional premium capabilities available through a paid subscription. | 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. |
| features.capabilities | `{"pricing_model":"freemium","deployment_model":"local_direct_imap_client","read_receipts_and_open_tracking":true,"snooze_and_scheduled_send_later":true,"unified_multi_account_inbox_view":true,"universal_imap_smtp_exchange_support":true}` | `{"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}` |
| integrations.count | 7 | - |
| integrations.list | `[{"name":"Gmail"},{"name":"iCloud"},{"name":"Office 365"},{"name":"FastMail"},{"name":"Outlook.com"},{"name":"Yahoo!"},{"name":"IMAP"},{"name":"SMTP"}]` | - |
| language.primary | TypeScript | Kotlin |
| license.spdx | GPL-3.0 | Apache-2.0 |
| market.availability | `{"primaryMarkets":[],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]}` | - |
| platform.support | `{"mac":true,"linux":true,"windows":true}` | `{"mac":true,"linux":true,"windows":true}` |
| pricing | `{"type":"hybrid","plans":[{"free":true,"name":"Free","features":["Unified Inbox","Snooze","Send Later","Mail Rules","Templates"],"description":"Open source version with core email features","contactSales":false},{"free":false,"name":"Mailspring Pro","features":["Link tracking","Read receipts","Mailbox analytics","Contact profiles","Company profiles"],"commitment":"monthly","description":"Premium subscription unlocking additional features","contactSales":false}],"summary":"Free open source core + monthly paid Pro tier","freeTier":true,"sourceUrl":"https://getmailspring.com","retrievedAt":"2026-10-05T10:08:40.523Z","billingPeriods":["month"]}` | `{"type":"free","summary":"Free, open-source. Free forever.","freeTier":true,"sourceUrl":"https://www.thunderbird.net","retrievedAt":"2026-08-21T12:42:28.376Z"}` |
| pricing.free_tier | yes | yes |
| pricing.model | freemium | freemium |
| pricing.price_level | low | free |
| pricing.starting_price | `{"amount":8,"currency":"USD"}` | - |
| pricing.transparent | no | yes |
| release.cadence_days | 12 | - |
| release.history | `[{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.26.0","date":"2026-10-02T14:37:36Z","type":"stable","version":"1.26.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.25.0","date":"2026-09-19T22:57:29Z","type":"stable","version":"1.25.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.24.1","date":"2026-09-15T02:13:24Z","type":"stable","version":"1.24.1"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.24.0","date":"2026-09-13T01:27:57Z","type":"stable","version":"1.24.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.23.0","date":"2026-07-22T03:45:22Z","type":"stable","version":"1.23.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.22.0","date":"2026-06-13T20:30:13Z","type":"stable","version":"1.22.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.21.1","date":"2026-05-20T20:31:26Z","type":"stable","version":"1.21.1"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.21.0","date":"2026-05-06T13:40:43Z","type":"stable","version":"1.21.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.20.1","date":"2026-04-20T16:07:46Z","type":"stable","version":"1.20.1"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.20.0","date":"2026-04-19T03:40:03Z","type":"stable","version":"1.20.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.19.1","date":"2026-04-07T01:34:03Z","type":"stable","version":"1.19.1"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.19.0","date":"2026-03-10T04:46:53Z","type":"stable","version":"1.19.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.18.0","date":"2026-02-23T14:40:58Z","type":"stable","version":"1.18.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.17.4","date":"2026-02-11T16:59:03Z","type":"stable","version":"1.17.4"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.17.3","date":"2026-01-31T20:21:11Z","type":"stable","version":"1.17.3"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.17.2","date":"2026-01-24T21:09:28Z","type":"stable","version":"1.17.2"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.17.1","date":"2026-01-15T20:55:25Z","type":"stable","version":"1.17.1"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.17.0","date":"2026-01-14T22:33:16Z","type":"stable","version":"1.17.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.16.0","date":"2025-07-16T14:29:44Z","type":"stable","version":"1.16.0"},{"url":"https://github.com/Foundry376/Mailspring/releases/tag/1.15.1","date":"2025-01-27T00:52:05Z","type":"stable","version":"1.15.1"}]` | `[{"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"}]` |
| 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 | Mailspring | Mozilla Thunderbird |
|---|:--:|:--:|
| **Capabilities** |  |  |
| Deployment model | Local direct imap client | 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 | Freemium | Free open source |

*Source: vioscaleAI. Generated 2026-10-16T19:21:55.991Z. "-" = undocumented, not absent.*