Mailspring

Mailspring is a native desktop email client for Mac, Windows, and Linux, built for people who send a lot of email and want more than basic send-and-receive. It connects to Gmail, iCloud, Office 365, Fastmail, Yahoo, and any IMAP/SMTP provider, pulling everything into a single unified inbox.

The free tier covers most daily needs: multi-account support, advanced search across all accounts, undo send, grammar and spell checking (powered by LanguageTool), custom signatures, dark mode, and localization into 12 languages with right-to-left layout support for Hebrew and Arabic. It also translates incoming and outgoing messages between English, Spanish, French, German, Russian, and simplified Chinese directly inside the composer.

Mailspring Pro ($8/month) adds the features that matter for professional communication:

• Read receipts and link tracking so you know when a message was opened and which links got clicks
• Send later and snooze to schedule outbound email and resurface threads at the right time
• Follow-up reminders to avoid letting important conversations go cold
• Quick reply templates for reusing outreach that works
• Contact and company profiles with bios, social links, timezone, headcount, and funding info pulled in alongside your conversations
• Mailbox insights showing open rates, click rates, and your busiest email hours

Under the hood, Mailspring uses a native C++ sync engine rather than wrapping a browser, which keeps RAM usage roughly half that of comparable clients and launch time under a second. Email syncs directly via IMAP, CalDAV, and CardDAV, so your messages go from your mail provider to your machine without passing through Mailspring's servers.

Compared to something like Spark Mail or Mailbird, Mailspring's main differentiators are its open codebase, direct sync architecture, and the combination of tracking features with a genuinely fast native interface. It runs on Linux including ARM64 and Wayland, which few desktop email clients bother to support properly.

Over 800,000 users have downloaded it since launch, and it's maintained by a small independent team with no outside investors.