Flectar Mail

This is a native email client built entirely in Rust, aimed at people tired of mail apps that eat hundreds of megabytes of memory. It runs on Windows, macOS, and Linux, with Android in experimental testing and iOS planned. It's still in active alpha, so expect preview builds.

Instead of embedding a browser engine, it uses its own Rust HTML and CSS renderer. That keeps memory use at roughly 20–140 MB and shrinks the attack surface. The project's own indicative figures put similar clients at 450–850 MB, though they're observations, not a controlled benchmark.

• Multiple providers: Gmail, Google Calendar and Contacts, Outlook, and Microsoft 365 in one workspace.
• Open standards: IMAP, SMTP, JMAP, CalDAV, CardDAV, and WebDAV, so you can connect self-hosted services.
• Calendar, contacts, files: CalDAV calendars, CardDAV address books, JMAP and WebDAV storage, attachment search, and file previews.
• Offline by design: mail and calendar data are stored locally, so synced information stays usable without a connection.
• Privacy defaults: remote images are blocked until you allow them, which stops tracking pixels from reporting reads.
• Desktop OpenPGP: sign and encrypt mail through GnuPG 2.x, with protected drafts kept local until sent.
• Customization: a three-pane layout or a minimal view, light and dark themes, built-in teal, green, and purple palettes, custom palettes, and optional sender avatars.

It also works with Flectar Base, the company's business email service with custom domains, shared addresses, and aliases. Because the client is open source, you can inspect exactly what handles your mail.