Sterna Mail

All your mail. None of the baggage. A fast, private JMAP email client for Android, fluent in classic IMAP/SMTP too. No ads. No tracking. No Google. ✨

Sterna Mail is open-source and built for JMAP, the new and faster internet standard for email, with full support for classic IMAP/SMTP too. Just your mail, on the server you choose.

🤔 Why JMAP? Most email apps talk to your server using an old protocol called IMAP. JMAP is its modern successor: it syncs faster, uses less battery and data, and was designed for today's phones. Servers like Stalwart speak JMAP, and Sterna is built to make the most of it. ⚡

Sterna also speaks classic IMAP and SMTP, so it works with any standard mail provider — pick the protocol when you add an account, or just type your email and let autodiscovery find the server for you.

💚 What Sterna stands for 🔒 Privacy first. No tracking, no ads, no analytics, no Google services. Remote images and tracking pixels are blocked by default; tapped links can be stripped of tracking parameters and confirmed before opening. 🆓 Free and open. Licensed under the GPLv3 — anyone can read, audit, and improve the code. 🎨 Modern and calm. A clean, fast Material 3 interface with its own brand identity that follows your phone's theme and language. ✨ Features 📥 Reading & organising

Unified inbox across multiple accounts (JMAP and/or IMAP/SMTP), fully offline (local cache); large folders page in as you scroll, fetching older mail from the server Conversation view — threads collapse into one row with a message count Nested folders shown as a collapsible tree; create / rename / delete, plus subfolders Configurable swipe actions, flag/star, archive & delete with undo, multi-select bulk actions, snooze, report spam, empty trash (with undo), sort and unread-only filter Search-as-you-type (server-side + instant local results) with advanced filters (from, subject, has-attachment, date) Calendar invites preview as an event card; one tap adds them to your calendar app (no calendar permission needed) ✍️ Writing & sending

Compose with recipient chips + autocomplete and email validation, multiple identities each with its own signature, attachments, and drafts Undo send, schedule send (with a screen to view/cancel pending sends), and "forgot attachment?" / large-recipient-list reminders 🔑 Accounts & setup

Add an account with just email + password (/.well-known/jmap autodiscovery), password-free OAuth 2.0 sign-in (device flow), or manual IMAP/SMTP with provider presets; a "test connection" button before saving Per-account colour, sync window, and notification toggle; encrypted credential storage (AndroidKeyStore); app lock (biometric / PIN) 🔒 Encryption

OpenPGP (via OpenKeychain): read and send signed and/or encrypted mail (PGP/MIME) on both JMAP and IMAP/SMTP. Decrypted content is never written to disk. See the encryption guide to get started. 🔔 Notifications & server power

Push for new mail with no Google / FCM (JMAP EventSource or IMAP IDLE), grouped per account, with quiet hours Server-side vacation responder and Sieve filter rules, mailbox quota display 🎨 Polish

Sterna's own Arctic (light) / Pelagic (dark) palette, optional Material You, adjustable message text size, settings export/import, a screen-reader-friendly UI, and coastal empty-state illustrations

🌍 Languages Sterna's interface is fully translated into nine languages:

🇬🇧 English · 🇫🇷 French · 🇩🇪 German · 🇪🇸 Spanish · 🇮🇹 Italian · 🇵🇹 Portuguese · 🇳🇱 Dutch · 🇷🇺 Russian · 🇵🇱 Polish

It also respects your system language out of the box, and you can override it per-app in Settings → Appearance.