Monochrome email client for Android — Jetpack Compose, Material 3 Expressive. No colour accents, no noise, just email.

Website · Download from Play Store · Discord

[!NOTE] Play Store Version: The app is currently in Open Testing on the Google Play Store (Paid). It includes full support for the Gmail API with instant Push Notifications, Microsoft Graph for Outlook, and IMAP.

[!IMPORTANT] Help Make Gmail Support Free: We are actively collecting funds to cover the expensive Google CASA Security Assessment required to verify the app and make Gmail API access free for everyone. If you'd like to support this effort, please consider donating on Ko-fi!

---

Features

Inbox

• Navigation: Pull-to-refresh, paginated scroll, scroll position retention per tab.
• Actions: Swipe gestures (configurable L/R), long-press actions, bulk multi-select, undo toast (4s), mark-all-read.
• Organization: Smart sender grouping, snooze (1hr/tomorrow/weekend/next week), date headers, calendar badge for scheduled.

Conversation & Detail View

• Threading: Collapsible thread view, inline chain view (configurable), thread connecting lines, alternating backgrounds, CC/BCC expand.
• Rendering: HTML rendering (WebView, JS disabled), algorithmic dark mode (AndroidX WebKit), responsive email detection.
• Security & Privacy: Remote image blocking with per-email override, CSP default-src 'none', HTML sanitization (no Jsoup).
• Viewing: Collapsible quoted text, inline image previews (max 280dp), attachment grid (2-4 columns), font scaling (0.8x-1.3x).

Search

• Local: Client-side filter (subject/sender/snippet).
• Remote: Server-side API search with pagination.

Multi-Account & Push Notifications

• Accounts: Up to 10 accounts (Gmail, Outlook, IMAP).
• Interface: Unified inbox toggle, swipe-to-switch avatar, profile card.
• Push: Instant Gmail Pub/Sub push notifications, Outlook Webhooks, and IMAP IDLE support. No more battery-draining polling—messages arrive the second they are sent.

Compose

• Basics: Reply/Reply-all/forward, CC/BCC, contact autocomplete, file attachments (any MIME).
• Advanced: Schedule send, undo send (5-30s configurable), send-as aliases, email templates.
• Editor: WebView contenteditable editor with formatting toolbar (B/I/U/lists/quote).

PGP Security

• Key Management: Ed25519/X25519 key generation, ASCII-armored import/export, passphrase-protected keys.
• Operations: Auto-decrypt + signature verification, encrypt & sign on outgoing.

Settings & Notifications

• Customization:
  • Appearance: Theme, font scale, dividers, compact mode, remote images, markdown, email colors.
  • Inbox: Swipe config, smart grouping.
  • Compose: Reply mode, confirm-send, undo window, templates.
  • Navigation: Dock size, tab editor.
• Background Sync: Adaptive WorkManager sync (2min foreground, 15min backoff), parallelized multi-account sync.
• Alerts: Per-account channels (sound/vibration), inline reply via RemoteInput, archive+undo from shade.

Micro-interactions

• Physics: Spring physics throughout (press-scale on cards/buttons, animated dock tabs, bounce on theme selector).
• Motion: animateContentSize for expand/collapse, sent overlay animation, slide+fade navigation transitions.

Extreme Optimizations

• Zero-Polling Battery Life: By moving to a Cloudflare Worker backend for Gmail Pub/Sub and Outlook Webhooks, combined with IMAP IDLE, the app sleeps until a push message wakes it up via FCM. Zero polling means minimal battery consumption.
• Compose Render Performance: Heavy use of remember, derivedStateOf, and immutable data classes to skip recompositions. List scrolling hits strict 120fps via lazy rendering and item keying.
• Database & Local Caching: SQLCipher + Room queries are heavily parallelized. We use adaptive paginated fetching with intelligent local caching so the app works seamlessly offline and loads instantly.
• Network Efficiency: Minimized payload sizes, batched API requests, and aggressive GZIP compression for all endpoints. Background sync is offloaded to WorkManager only when necessary, adapting to your network state.

Account management

• Gmail — Android Credential Manager + Google Identity Services
• Outlook — MSAL 5.4.0 with silent token refresh
• IMAP/SMTP — provider presets (Gmail, Outlook, Yahoo, Zoho, Custom) with connection testing
• AES-GCM encrypted credential storage (Android KeyStore)
• Provider-scoped sign-out

Architecture

flowchart TB
    subgraph UI [Compose UI]
        Inbox
        Detail
        Compose
        Settings
        Auth
    end

    subgraph Data [Data Layer]
        Repo[EmailRepo]
        AuthMgr[Auth]
        SettingsDS[Settings]
    end

    subgraph Local [Local Storage]
        Room[(Room + SQLCipher)]
        DataStore[(DataStore)]
        KeyStore[KeyStore]
    end

    subgraph Remote [Remote]
        Gmail[Gmail API]
        Outlook[Outlook API]
        IMAP[IMAP/SMTP]
        Push[FCM Push]
    end

    UI --> Data
    Data --> Local
    Data --> Remote
    Push -.->|background| Data

Layer	Technology
UI	Jetpack Compose, Material 3 Expressive, Navigation Compose
Language	Kotlin 2.2
DI	Hilt
Networking	Retrofit 2, OkHttp 4
Database	Room + SQLCipher
Auth	Google Credential Manager, MSAL 5.4.0
IMAP/SMTP	Eclipse Angus Mail (Jakarta Mail 2.x)
PGP	PGPainless 2.0.3 (Bouncy Castle)
Images	Coil Compose
Markdown	Markwon 4.6.2
Background	WorkManager + ActionQueueManager
Secure storage	AndroidX Security Crypto

Getting Started

Prerequisites

• Android Studio Ladybug+
• JDK 17+
• Google Cloud project with Gmail API enabled
• Azure App Registration (Outlook/Microsoft Graph — scopes: Mail.Read, Mail.ReadWrite, Mail.Send, User.Read; redirect URI: msal{client_id}://auth)

Setup

git clone https://github.com/shrivatsav-org/monomail.git

Create secrets.properties for the playstore flavor:

GOOGLE_CLIENT_ID=your_web_client_id_here

Configure MSAL (optional — app/src/main/res/raw/msal_config.json):

{
  "client_id": "your_msal_client_id",
  "authorities": [{"type": "AAD", "audience": "AzureADandPersonalMicrosoftAccount"}],
  "redirect_uri": "msal{your_client_id}://auth"
}

Minimum SDK: 26 (Android 8.0).

Builds

Flavor	Description
playstore	Bundled with the developer's official Google OAuth Web Client ID. Push notifications via FCM.
github	Excludes private OAuth client ID. Google Sign-In temporarily disabled during OAuth verification — use Outlook or IMAP in the meantime.

./gradlew installPlaystoreDebug   # or installGithubDebug

Contributing

PRs welcome. Open an issue first for significant changes.

Fork → Branch → Commit → Pull Request

License

GPL-3.0

---

Built by Shrivatsav