Configuration

mail uses environment variables for process-level configuration and PostgreSQL for values saved through setup or Settings. Feature-specific setting and environment names live with the feature they control instead of in one global variable catalog.

Configuration files

• .env.example is the web-process template and includes optional feature fallbacks.
• .env.example.worker is a smaller template for a separately managed worker.
• A shared .env can be supplied to both processes, as in the repository's Docker Compose file.

Do not commit populated environment files. Give web and worker only the values each process needs.

Precedence

Non-empty values saved through setup or Settings take precedence over scalar authentication, AI, IMAP, and SMTP environment variables. Environment variables remain fallbacks. Additional IMAP and SMTP arrays saved in PostgreSQL and supplied through the environment are both loaded.

DATABASE_URL, ORIGIN, BETTER_AUTH_SECRET, and MAIL_SECRET_KEY are environment-only. The settings cache refreshes within about five seconds after a change. Boolean mail fallbacks use the string false to disable a value; other non-empty values enable it.

Core process settings

Variable	Process	Default	Requirement
DATABASE_URL	web, worker	none	PostgreSQL connection URL. Required outside demo mode. Both processes must use the same database.
ORIGIN	web, worker	none	Exact public HTTP or HTTPS origin, including a non-standard port. Required for authentication and used by tracking and callback URLs.
BETTER_AUTH_SECRET	web	none	Required outside demo mode. Use an independent high-entropy value of at least 32 characters in production.
MAIL_SECRET_KEY	web, worker	empty	Encrypts stored credentials and private keys. Keep it stable, identical across processes, and backed up.
DEMO_MODE	web, worker	false	Accepts 1, true, yes, or on; see Demo mode.

Generate independent secrets with openssl rand -base64 32. Losing or changing MAIL_SECRET_KEY makes values already encrypted with it unreadable.

Runtime tuning

Variable	Process	Default	Description
PG_POOL_MAX	web, worker	10	Maximum PostgreSQL connections per process. The worker example uses 5.
PG_TLS_REJECT_UNAUTHORIZED	web, worker	true	Set to false only for a trusted PostgreSQL server with a private or self-signed certificate. It does not affect HTTPS, IMAP, or SMTP.
HOST	web	0.0.0.0	Production Node server listen address.
PORT	web	3000	Production Node server listen port.
BODY_SIZE_LIMIT	web	Infinity	SvelteKit request-body limit. Accepts bytes or a value with K, M, or G. See Composing and sending.
NODE_ENV	web, worker	unset	Set to production for production source deployments. Container images set it automatically.
TZ	worker	Asia/Seoul	Timezone used only when formatting an IMAP cooldown timestamp in worker logs.

Feature configuration

Use the relevant feature page for exact Settings labels, environment names, defaults, and requirements:

Feature	Configuration page
IMAP and SMTP accounts	Mail accounts
Authentication providers, passkeys, and sessions	Authentication
AI and automatic importance	AI features
Public-link and direct attachments	Composing and sending
OpenPGP private-key storage	OpenPGP
Remote-content privacy	Privacy controls
SPF, DKIM, and DMARC trust	Mail authentication
Push and quiet hours	Push notifications
Outgoing read tracking	Read tracking
Public IMAP listener	Public IMAP proxy
REST API and MCP	External API and MCP

The feature overview links every feature page, including features with Settings-only configuration and no environment variable.