What is Mailspring used for?

Mailspring is an open-source desktop email client for Mac, Windows and Linux with a unified inbox, snooze, send later and a local sync engine. It is a good fit for managing several mailboxes from one desktop app and replacing a browser-based email workflow.

Is Mailspring open source?

Yes. Mailspring is open source under the GPL-3.0 licence. Its source code is on GitHub at Foundry376/Mailspring and is written mainly in TypeScript.

Yes. Mailspring is open source, so the software itself is free to use. Paid plans are also available, starting at $8 per month.

Can I self-host Mailspring?

Yes. Mailspring can be self-hosted on your own server or infrastructure; there is no official hosted version.

What is Mailspring an alternative to?

Mailspring is an open-source alternative to Microsoft Outlook, Spark Mail, Mailbird and Superhuman. Other open-source alternatives to Microsoft Outlook include Thunderbird, Thunderbird for Android and FairEmail.

Is Mailspring actively maintained?

Yes. The most recent commit to Mailspring was on 2 October 2026, and the latest release is 1.26.0, published on 2 October 2026. The project has 18k stars on GitHub.

Mailspring: open-source alternative to Microsoft Outlook

About Mailspring

Mailspring is a desktop email client for Mac, Windows and Linux, built as a new version of Nylas Mail by one of its original authors. The interface is written in TypeScript with Electron and React, and the mail sync engine is written in C++ and runs locally on your computer. Both parts are open source under GPLv3.

Features include a unified inbox, snooze, send later, mail rules and templates, and a plugin architecture makes the app easy to extend. The README states that these features run in the client and that email credentials are not sent to the cloud. The IMAP-based sync engine replaces the earlier JavaScript sync code used by Nylas Mail.

A paid Mailspring Pro subscription unlocks extra features for people who send a lot of email, such as link tracking, read receipts, mailbox analytics and contact and company profiles. Compiled downloads are offered for Windows, macOS and Linux, including deb, rpm and snap packages.

Key features

Unified inbox across accounts
Snooze and send later
Mail rules and templates
Plugin architecture for extensions
Local C++ sync engine
Pro tier adds tracking and analytics

Good fit for

→Managing several mailboxes from one desktop app
→Replacing a browser-based email workflow

Built with: TypeScript; Electron
Tags: email; mail-client; desktop; electron; imap; gpl; unified-inbox; productivity

Mailspring: questions and answers

What is Mailspring used for?: Mailspring is an open-source desktop email client for Mac, Windows and Linux with a unified inbox, snooze, send later and a local sync engine. It is a good fit for managing several mailboxes from one desktop app and replacing a browser-based email workflow.
Is Mailspring open source?: Yes. Mailspring is open source under the GPL-3.0 licence. Its source code is on GitHub at Foundry376/Mailspring and is written mainly in TypeScript.
Is Mailspring free?: Yes. Mailspring is open source, so the software itself is free to use. Paid plans are also available, starting at $8 per month.
Can I self-host Mailspring?: Yes. Mailspring can be self-hosted on your own server or infrastructure; there is no official hosted version.
What is Mailspring an alternative to?: Mailspring is an open-source alternative to Microsoft Outlook, Spark Mail, Mailbird and Superhuman. Other open-source alternatives to Microsoft Outlook include Thunderbird, Thunderbird for Android and FairEmail.
Is Mailspring actively maintained?: Yes. The most recent commit to Mailspring was on 2 October 2026, and the latest release is 1.26.0, published on 2 October 2026. The project has 18k stars on GitHub.