Sia E-Mail Client

About

Sia E-Mail Client is a secure, clean Android email client built entirely on open standards — IMAP/SMTP, JMAP (RFC 8620/8621), and OAuth2 — with no dependency on patented proprietary protocols (it deliberately does not implement Exchange ActiveSync). Connect Gmail, Outlook/Hotmail/Live, Microsoft 365, Yahoo, iCloud, Naver, and Daum/Kakao, then read and write mail through modern, standards-based paths. Built with Kotlin, Jetpack Compose, and Material 3, following an MVVM + Repository architecture over Room, WorkManager, and DataStore. Your accounts, messages, and credentials sync directly between your device and your own mail servers and OAuth providers — there is no Sia Makerlab server in the path.

Features

• Multiple accounts with a cross-account unified inbox, provider presets, and manual IMAP/SMTP configuration
• OAuth2 login (Authorization Code + PKCE via Custom Tabs) using XOAUTH2 for Outlook, Microsoft 365, and Gmail, with automatic refresh-token renewal; JMAP accounts also supported
• Connection testing, certificate validation, and enforced TLS — plaintext connections are rejected by default
• Folder-tree sidebar with smart views (all inboxes, all unread, starred, snoozed) and on-device smart category tabs (newsletters, promotions, social, notifications)
• Reading with remote-image blocking, attachment download/open, ICS calendar-invite parsing, and on-device AI summarization that runs locally with no network calls
• Compose, reply, and forward with Markdown rich text, signatures, scheduled send, snooze, and templates; mark-all-read by folder, account, or all; customizable swipe actions
• Credentials encrypted with Android Keystore (AES-256-GCM), biometric/PIN app lock, and OpenPGP and S/MIME end-to-end encryption
• On-device spam/phishing heuristics with sender-spoofing and link-domain-mismatch warnings
• New-mail notifications with per-account grouping, summaries, and Mark-read/Archive actions plus Wear OS actions — driven by background sync, with no push server