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Environment Reference

This page documents every setting currently present in Bulwark's .env.example and a handful of additional advanced variables read by the app.

All variables are evaluated at runtime, so Docker deployments can be reconfigured without rebuilding. Some are always available, some only affect optional features, and a few exist as compatibility fallbacks for older build-time deployments. The single exception is NEXT_PUBLIC_BASE_PATH, which Next.js bakes into asset URLs at build time.

First-launch tip Most new installs no longer need to set environment variables by hand - launch the container without JMAP_SERVER_URL and the web setup wizard writes the equivalent values to ADMIN_CONFIG_DIR. Use env vars when you want env-driven, immutable, or read-only configuration.

Server Listen Address

HOSTNAME

  • Purpose - Sets the address the server binds to.
  • Required - No.
  • Default - 0.0.0.0
  • When to set it - Set to :: to listen on IPv6 (dual-stack), or to a specific interface address to restrict access.

PORT

  • Purpose - Sets the port the server listens on.
  • Required - No.
  • Default - 3000
  • When to set it - Set this when you need the server to listen on a non-default port.

Core Settings

APP_NAME

  • Purpose - Sets the application name displayed in the UI, browser tab title, and PWA manifest.
  • Required - No.
  • Default - Webmail (built-in fallback when not set).
  • When to set it - Set this if you want your deployment to be branded differently from the default Bulwark name.

APP_SHORT_NAME

  • Purpose - Short name for the app, used where space is limited (home screen label on mobile, PWA install prompt).
  • Required - No.
  • Default - Falls back to APP_NAME if not set.

APP_DESCRIPTION

  • Purpose - Description shown in the PWA manifest (displayed by the OS during install).
  • Required - No.
  • Default - Generic Bulwark description.

JMAP_SERVER_URL

  • Purpose - Points Bulwark to your JMAP-compatible mail server. Setting this also disables the first-launch setup wizard.
  • Required - No - the setup wizard can write this value to admin config instead. Required only when you want env-driven configuration, when ALLOW_CUSTOM_JMAP_ENDPOINT=true is not set, or when you rely on the legacy NEXT_PUBLIC_JMAP_SERVER_URL fallback.
  • Example - https://mail.example.com
  • Multi-server - Accepts a comma-separated list of URLs for deployments that fan out across multiple JMAP servers. The login form auto-picks by email domain when possible; users can still choose a server manually.
  • When to set it - For env-driven deployments, or when you want to lock the JMAP server choice and hide it from the admin UI.

ALLOW_CUSTOM_JMAP_ENDPOINT

  • Purpose - Shows a "JMAP Server" field on the login form so users can connect to any JMAP-compatible server.
  • Required - No.
  • Default - false
  • CORS note - External JMAP servers must include the webmail origin in their Access-Control-Allow-Origin response header, or browser requests will be blocked.
  • When to set it - Set to true for multi-tenant deployments or testing setups where users connect to different servers.

Stalwart Integration

STALWART_FEATURES

  • Purpose - Enables Stalwart-specific features such as password change, Sieve management, vacation responder controls, account security, API keys, and the admin dashboard.
  • Required - No.
  • Default - true unless explicitly set to false.
  • When to set it - Set STALWART_FEATURES=false if you are using Bulwark with a non-Stalwart JMAP server and want to hide features that depend on Stalwart-specific JMAP x: methods.

STALWART_API_URL (deprecated in 1.5.0)

  • Status - Deprecated. Stalwart 0.16 dropped its REST self-service HTTP API and replaced it with JMAP. Bulwark now talks to the JMAP endpoint exclusively, so this variable has no effect.
  • Migration - Remove from your .env.local. The self-service portal (account settings, app passwords, API keys) requires Stalwart 0.16 or newer.

OAuth / OpenID Connect

OAUTH_ENABLED

  • Purpose - Turns on OAuth2 / OIDC login support.
  • Required - No.
  • Default - false
  • When to set it - Set to true when your deployment should show an SSO login flow.

OAUTH_ONLY

  • Purpose - Makes OAuth the only login method and hides the username/password form.
  • Required - No.
  • Dependency - Requires OAUTH_ENABLED=true.
  • When to set it - Use this when all users should authenticate through your identity provider only.

OAUTH_CLIENT_ID

  • Purpose - OAuth client ID registered with your identity provider.
  • Required - Required when OAuth is enabled.
  • When to set it - Always set this together with OAUTH_ENABLED=true.

OAUTH_CLIENT_SECRET

  • Purpose - OAuth client secret used for confidential clients.
  • Required - No.
  • When to set it - Only needed if your IdP registration expects a confidential client instead of a public PKCE-only client.

OAUTH_CLIENT_SECRET_FILE

  • Purpose - Path to a file containing the OAuth client secret.
  • Required - No.
  • When to set it - Use this with Docker secrets, Kubernetes secrets, or any platform that mounts secrets as files. If both OAUTH_CLIENT_SECRET and OAUTH_CLIENT_SECRET_FILE are set, the env var takes precedence.

OAUTH_ISSUER_URL

  • Purpose - Explicit issuer URL used for OIDC discovery.
  • Required - No.
  • Default behavior - If omitted, Bulwark falls back to discovery through JMAP_SERVER_URL.
  • When to set it - Set this when your mail server delegates auth to an external IdP such as Keycloak or Authentik.

OAUTH_SCOPES

  • Purpose - Override the OAuth scope string requested at the authorization endpoint.
  • Required - No.
  • Default - Built-in default scopes appropriate for JMAP and OIDC.
  • When to set it - Only when your IdP requires a specific scope set.

OAUTH_EXTRA_SCOPES

  • Purpose - Append extra scopes to the default scope set without replacing it.
  • Required - No.
  • Default - Empty.
  • When to set it - When you need to add provider-specific scopes (e.g., a custom audience scope) on top of the defaults.

Session & Security

SESSION_SECRET

  • Purpose - Secret used to encrypt persistent "Remember me" sessions, settings sync data, multi-account state, and server-side OAuth PKCE state.
  • Required - Optional for basic login. Required for: encrypted persistent sessions, settings sync, multi-account support, and embedded SSO.
  • Generation - openssl rand -base64 32
  • Validation - Strict minimum length is enforced.

SESSION_SECRET_FILE

  • Purpose - Path to a file containing the session secret.
  • Required - No.
  • When to set it - Use with Docker secrets or Kubernetes secrets. SESSION_SECRET takes precedence if both are set.
  • Purpose - Sets the SameSite attribute on session cookies.
  • Allowed values - lax, none, strict
  • Default - lax
  • When to set it - Set to none when Bulwark is embedded cross-origin in an iframe. Requires HTTPS.
  • Purpose - Force cookies to be marked as Secure.
  • Required - No.
  • Default - true when COOKIE_SAME_SITE=none or NODE_ENV=production, otherwise false.
  • When to set it - Override when reverse-proxying terminates TLS in front of an http:// Bulwark and you need explicit control.

Settings Sync

SETTINGS_SYNC_ENABLED

  • Purpose - Enables encrypted server-side settings persistence across devices and accounts.
  • Required - No.
  • Dependency - Requires SESSION_SECRET.
  • Default - false
  • When to set it - Set to true when you want settings to follow users across browsers, devices, and accounts.

SETTINGS_DATA_DIR

  • Purpose - Filesystem location where encrypted settings files are stored.
  • Required - No.
  • Default - ./data/settings (resolves to /app/data/settings in Docker, since WORKDIR is /app)
  • When to set it - Set this when you want settings data stored on a specific persistent volume or host path.
  • Docker note - Mount a persistent volume at /app/data/settings (or at whatever absolute path you configure) so that settings survive container restarts: 
    volumes:
  - bulwark-settings:/app/data/settings

Admin Dashboard

ADMIN_PASSWORD

  • Purpose - Sets the initial admin password for the local admin dashboard. The dashboard manages plugins, themes, runtime config overrides, and policy.
  • Required - No - the setup wizard prompts for an initial password instead.
  • Default - On first startup with no password set and no wizard completion, a random password is generated and logged to stdout.
  • When to set it - Set this when you want env-driven configuration or to override whatever the wizard wrote.

ADMIN_CONFIG_DIR (new in 1.6.4)

  • Purpose - Operator-authored admin state. Holds config.json, policy.json, admin.json (passwordHash only), plugin-config/, plugins/, themes/, and uploaded branding assets. Safe to mount read-only after the setup wizard finishes.
  • Required - No.
  • Default - ./data/admin (resolves to /app/data/admin in Docker). Falls back to ADMIN_DATA_DIR for back-compat.
  • Docker note - Mount a persistent volume - read/write during initial setup, optionally read-only afterwards: 
    volumes:
  - bulwark-config:/app/data/admin       # rw during setup
  # - bulwark-config:/app/data/admin:ro  # ro after setup completes

ADMIN_STATE_DIR (new in 1.6.4)

  • Purpose - Runtime admin state that must stay writable forever: admin-state.json (login timestamps), audit.log, and the bootstrap setup token.
  • Required - No.
  • Default - ./data/admin-state (resolves to /app/data/admin-state in Docker). When ADMIN_DATA_DIR is set without the split vars, Bulwark uses <ADMIN_DATA_DIR>/state for back-compat.
  • Docker note - Always read-write: 
    volumes:
  - bulwark-state:/app/data/admin-state

ADMIN_CONFIG_READONLY (new in 1.6.4)

  • Purpose - Enforce read-only mode at the application layer so attempts to mutate config produce a clean error rather than a mid-request EROFS from the filesystem.
  • Required - No.
  • Default - false
  • When to set it - Pair with :ro on the ADMIN_CONFIG_DIR mount after the wizard completes. Useful for immutable infrastructure (Kubernetes / Talos / read-only root).

ADMIN_DATA_DIR (legacy)

  • Purpose - Single directory containing both config and state for pre-1.6.4 installs.
  • Required - No.
  • Default - Not set.
  • Behavior - Honoured only when neither ADMIN_CONFIG_DIR nor ADMIN_STATE_DIR is set. New installs should use the split variables.

ADMIN_SESSION_TTL

  • Purpose - Admin session lifetime in seconds.
  • Required - No.
  • Default - Built-in safe default.

TRUSTED_PROXY_DEPTH

  • Purpose - Number of X-Forwarded-For hops to trust when resolving the client IP for admin sessions and audit logs.
  • Required - No.
  • Default - 1
  • When to set it - Increase if Bulwark sits behind multiple reverse proxies (e.g., CDN -> ingress -> app).

Anonymous Telemetry

BULWARK_TELEMETRY

  • Purpose - Master toggle for the anonymous daily heartbeat. Heartbeats contain no PII (version, platform, feature toggles, bucketed account counts).
  • Required - No.
  • Default - On.
  • When to set it - Set to off (or disabled) to turn telemetry off without going through the admin UI. The env var wins over the UI toggle.
  • See also - Anonymous Usage Stats and Telemetry privacy.

BULWARK_TELEMETRY_URL

  • Purpose - Endpoint the heartbeat is sent to.
  • Required - No.
  • Default - https://telemetry.bulwarkmail.org/v1/heartbeat.
  • When to set it - Point at your own collector (open-source under telemetry-collector/), or clear it (BULWARK_TELEMETRY_URL=) to disable.

TELEMETRY_DATA_DIR

  • Purpose - Directory for telemetry state: the random instance_id, the admin's consent choice, and HMAC'd login fingerprints used to compute the 7-day-active-accounts bucket.
  • Required - No.
  • Default - ./data/telemetry (resolves to /app/data/telemetry in Docker).
  • Docker note - Mount a persistent volume so the instance id and consent choice survive upgrades: 
    volumes:
  - bulwark-telemetry:/app/data/telemetry

Extension Directory / Marketplace

EXTENSION_DIRECTORY_URL

  • Purpose - URL of the BulwarkMail extension directory used by the admin marketplace for browsing and installing plugins and themes.
  • Required - No.
  • Default - Empty (marketplace disabled).
  • Example - https://extensions.bulwarkmail.org
  • When to set it - Set this to enable the marketplace browse-and-install UI in the admin dashboard.

Logging

LOG_FORMAT

  • Purpose - Controls server log output format.
  • Allowed values - text (colored, human-readable), json (structured)
  • Default - text
  • When to set it - Use json for centralized log aggregation in containers and observability stacks.

LOG_LEVEL

  • Purpose - Controls server log verbosity.
  • Allowed values - error, warn, info, debug
  • Default - info
  • When to set it - Increase to debug during troubleshooting; lower to warn or error in quieter production environments.

Branding - Icons & Favicon

FAVICON_URL

  • Purpose - Custom favicon shown in the browser tab.
  • Required - No.
  • Default - Bulwark favicon (/branding/Bulwark_Favicon.svg).
  • Accepted values - Absolute URL or path relative to public/.
  • Supported formats - SVG (recommended), PNG, ICO.
  • Recommended size - 32×32px minimum, 512×512px maximum. SVG is preferred for crisp scaling.

PWA_ICON_URL

  • Purpose - Source image used to auto-generate the PWA install icons (192×192 and 512×512 PNG, plus maskable variants).
  • Required - No.
  • Default - Falls back to FAVICON_URL, then to the default Bulwark icons.
  • Accepted values - Absolute URL or path relative to public/.
  • Supported formats - SVG (recommended for best quality) or PNG (≥512×512px recommended).

PWA_THEME_COLOR

  • Purpose - Color applied to the browser UI chrome when the app is installed as a PWA (address bar, Android status bar).
  • Required - No.
  • Default - #ffffff
  • Example - #3b82f6

PWA_BACKGROUND_COLOR

  • Purpose - Background color shown on the PWA splash screen while the app is loading.
  • Required - No.
  • Default - #ffffff
  • When to set it - Match your app's main background color.

Branding - Logos

APP_LOGO_LIGHT_URL

  • Purpose - Logo shown in the sidebar on light backgrounds (main app, after login).
  • Required - No.
  • Default - Empty (no sidebar logo).
  • Accepted values - Absolute URL or path relative to public/.
  • Supported formats - SVG (recommended), PNG, WebP.
  • Recommended size - 24×24px minimum, 128×128px maximum. Displayed at 24×24px.

APP_LOGO_DARK_URL

  • Purpose - Logo shown in the sidebar on dark backgrounds (main app, after login).
  • Required - No.
  • Default - Empty (falls back to APP_LOGO_LIGHT_URL if set, otherwise no logo).

Login Page Customization

LOGIN_LOGO_LIGHT_URL

  • Purpose - Logo shown on light backgrounds on the login page.
  • Required - No.
  • Default - Bulwark light logo.
  • Recommended size - 32×32px minimum, 512×512px maximum. Displayed at 64×64px.

LOGIN_LOGO_DARK_URL

  • Purpose - Logo shown on dark backgrounds on the login page.
  • Required - No.
  • Default - Bulwark dark logo.

LOGIN_COMPANY_NAME

  • Purpose - Company or organization name shown above the version on the login page.

LOGIN_IMPRINT_URL

  • Purpose - Adds an imprint / legal notice link to the login page.

LOGIN_PRIVACY_POLICY_URL

  • Purpose - Adds a privacy policy link to the login page.

LOGIN_WEBSITE_URL

  • Purpose - Adds a website link to the login page.

Internationalization

NEXT_PUBLIC_LOCALE_PREFIX

  • Purpose - Controls how the locale appears in URLs (e.g., /en/inbox vs /inbox).
  • Allowed values - always (always prefix), as-needed (only for non-default locales), never (never prefix).
  • Default - Built-in safe default.
  • When to set it - Match the routing strategy you want for SEO, redirects from older deployments, or middleware compatibility. Set to always when using NEXT_PUBLIC_BASE_PATH to avoid next-intl rewrite loops.

Subpath / Reverse Proxy Mount

NEXT_PUBLIC_BASE_PATH (build-time)

  • Purpose - Mount Bulwark under a URL prefix (e.g. https://example.com/webmail).
  • Required - No.
  • Default - Empty (served from the root).
  • Build-time - Unlike most other variables, this is read at build time because Next.js bakes it into emitted asset URLs.
  • When to set it - Set this when fronting Bulwark with a reverse proxy that exposes it under a subpath. Pair with NEXT_PUBLIC_LOCALE_PREFIX=always and do not strip the prefix at the proxy - the app expects to receive requests under /<base-path>/... and serves all routes (/<base-path>/api/..., /<base-path>/_next/static/..., /<base-path>/sw.js, etc.) accordingly.
  • Docker note - To use this with the published image, build your own with the build arg set: 
    docker build --build-arg NEXT_PUBLIC_BASE_PATH=/webmail -t bulwark-webmail .

Embedded SSO & iframe

AUTO_SSO_ENABLED

  • Purpose - Automatically start the OAuth flow on the login page without user interaction.
  • Required - No.
  • Default - false
  • Dependency - Requires OAUTH_ENABLED=true and OAUTH_ONLY=true.
  • When to set it - Set to true when embedding Bulwark in an iframe with automatic SSO managed by a parent portal.

ALLOWED_FRAME_ANCESTORS

  • Purpose - Sets the CSP frame-ancestors directive to allow embedding in an iframe.
  • Required - No.
  • Default - 'none' (iframe embedding disabled).
  • When to set it - Set to the origin of the parent portal (e.g., https://portal.example.com).

NEXT_PUBLIC_PARENT_ORIGIN

  • Purpose - Origin of the parent frame for validating incoming postMessage events.
  • Required - No.
  • Default - Empty (accepts messages from any origin).
  • When to set it - Set to the origin of the parent portal for security when using the postMessage bridge.

Legacy Build-time Fallbacks

These variables still work, but they exist for compatibility with older deployments where values were baked into the frontend bundle at build time.

NEXT_PUBLIC_APP_NAME

  • Purpose - Legacy fallback for APP_NAME.
  • Required - No.
  • When to use it - Only if you still depend on build-time configuration.

NEXT_PUBLIC_JMAP_SERVER_URL

  • Purpose - Legacy fallback for JMAP_SERVER_URL.
  • Required - No.
  • When to use it - Only if you still depend on build-time configuration.

Small self-hosted setup

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com

Stalwart with encrypted persistent sessions

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com
SESSION_SECRET=replace-with-a-random-secret

Stalwart with cross-device settings sync

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com
SESSION_SECRET=replace-with-a-random-secret
SETTINGS_SYNC_ENABLED=true
SETTINGS_DATA_DIR=/data/settings

Multi-account with extension marketplace

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com
SESSION_SECRET=replace-with-a-random-secret
SETTINGS_SYNC_ENABLED=true
EXTENSION_DIRECTORY_URL=https://extensions.bulwarkmail.org
ADMIN_PASSWORD=replace-with-a-strong-admin-password

Custom PWA branding

APP_NAME=Acme Mail
APP_SHORT_NAME=Acme
APP_DESCRIPTION=Acme Corporation webmail
JMAP_SERVER_URL=https://mail.acme.com
FAVICON_URL=/branding/acme-favicon.svg
PWA_ICON_URL=/branding/acme-icon.svg
PWA_THEME_COLOR=#0f172a
PWA_BACKGROUND_COLOR=#ffffff
APP_LOGO_LIGHT_URL=/branding/acme-logo-color.svg
APP_LOGO_DARK_URL=/branding/acme-logo-white.svg

OAuth-only deployment

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com
OAUTH_ENABLED=true
OAUTH_ONLY=true
OAUTH_CLIENT_ID=webmail
OAUTH_ISSUER_URL=https://id.example.com/realms/mail

Non-Stalwart JMAP server

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com
STALWART_FEATURES=false

Embedded SSO in an iframe

APP_NAME=Bulwark Webmail
JMAP_SERVER_URL=https://mail.example.com
OAUTH_ENABLED=true
OAUTH_ONLY=true
OAUTH_CLIENT_ID=webmail
OAUTH_ISSUER_URL=https://auth.example.com
SESSION_SECRET=replace-with-a-random-secret
AUTO_SSO_ENABLED=true
ALLOWED_FRAME_ANCESTORS=https://portal.example.com
COOKIE_SAME_SITE=none
NEXT_PUBLIC_PARENT_ORIGIN=https://portal.example.com

Behind multiple reverse proxies

JMAP_SERVER_URL=https://mail.example.com
SESSION_SECRET=replace-with-a-random-secret
TRUSTED_PROXY_DEPTH=2

Using *_FILE Variables With Docker Secrets

Several variables that hold secrets accept a corresponding *_FILE variant pointing at a file containing the value. This is the recommended pattern when running under Docker Swarm, Kubernetes, or any orchestration platform that mounts secrets as files:

services:
  bulwark:
    image: ghcr.io/bulwarkmail/webmail:latest
    environment:
      JMAP_SERVER_URL: https://mail.example.com
      SESSION_SECRET_FILE: /run/secrets/session_secret
      OAUTH_CLIENT_SECRET_FILE: /run/secrets/oauth_secret
    secrets:
      - session_secret
      - oauth_secret

secrets:
  session_secret:
    external: true
  oauth_secret:
    external: true

If both the env var (e.g., SESSION_SECRET) and the _FILE variant (e.g., SESSION_SECRET_FILE) are set, the env var takes precedence.