ElecPostal

Go implementation of the Solar Network email service.

Run

cp config.example.toml config.toml
# edit config.toml
go run ./cmd

Logging

• ZEROLOG_PRETTY=true enables console-style pretty logs
• LOG_LEVEL=debug|info|warn|error sets the log level

Config

Use --config or CONFIG_PATH for a TOML config file.

Key settings:

• app.name
• database.dsn
• http.port
• grpc.port
• grpc.useTLS
• auth.target
• auth.useTLS
• filesystem.target (optional FileSystem gRPC endpoint for inbound email attachments)
• workspace.target (Workspace gRPC endpoint required for workspace mailbox authorization and plan-based mail quotas)
• ring.target (optional Ring gRPC endpoint for account notifications)
• mail.domain (canonical mail domain; local-only mailbox addresses are completed with this domain before outbound delivery and exposed via GET /api/mail/host)

Attachments

Clients upload outgoing attachments to DysonFS first, then submit the returned file IDs as the attachment_ids string array to POST /api/emails. Inbound delivery and protocol APPEND stream decoded attachment bytes to DysonFS before ElecPostal persists message metadata. ElecPostal never stores attachment bytes in PostgreSQL or durable NATS jobs.

Workspace email quota

• Mailboxes belong to a workspace. ElecPostal accounts for message text, headers, recipients, and manifest metadata in its own quota. DysonFS owns attachment bytes and reports that storage separately; Valve aggregates both services and periodically refreshes the workspace usage snapshot. When the shared limit is exceeded, ElecPostal archives the oldest messages and permanently removes their metadata after 30 days.

Outbound send limits

Outbound messages are counted both per mailbox and across the workspace. The defaults are configurable under mail.sendLimits.free, mail.sendLimits.pro, and mail.sendLimits.enterprise; each plan has mailboxDaily, mailboxMonthly, workspaceDaily, and workspaceMonthly values. Set a value to 0 to disable that specific limit. Drafts do not consume quota; scheduled messages consume it when they are delivered.

Credentials

Create scoped, revocable app passwords at POST /api/credentials with a mailbox_id, label, and one or more protocols (smtp, imap, pop3). The returned secret is shown once and is only accepted by that mailbox address's protocol listeners—not by HTTP APIs or another address on the same account.

Protocol storage

ElecPostal stores protocol metadata and an attachment-free MIME manifest with each message. DysonFS is the only durable attachment-byte store. IMAP and POP3 generate RFC 5322 responses on demand by streaming referenced DysonFS files; boundaries are generated per response. This pre-release service uses GORM AutoMigrate plus a startup migration for legacy raw sources. The provided docker-compose.yml starts PostgreSQL, JetStream, Redis, and ElecPostal. Configure TLS certificates for all enabled SMTP, IMAP, and POP3 listeners.

JMAP

JMAP is available over the main HTTPS listener at GET /jmap/session and POST /jmap/api. It uses the same bearer-token authentication as the REST API. Each hosted address is a JMAP account and IMAP folders are JMAP Mailboxes. This initial support includes Core/echo, Mailbox/get, Mailbox/query, Email/get, Email/query, and Email/set for flags, moves, and trashing. JMAP reads and updates the same message state as IMAP and POP3.

Outbound delivery

Set mail.relay.adapter = "direct-smtp" to deliver directly to recipient MX records without a relay. mail.relay.host must be this server's public mail hostname for EHLO. Direct delivery uses TCP port 25 and opportunistically uses STARTTLS; set mail.relay.tlsMode = "required" to reject MX servers that do not support STARTTLS.

Set mail.relay.adapter = "ses" to use the AWS SDK's SES API v2 client. Set mail.relay.region and authenticate through the AWS SDK default credential chain (for example, an IAM role, AWS_ACCESS_KEY_ID/AWS_SECRET_ACCESS_KEY, or an AWS shared profile). SES SMTP credentials and mail.relay.host are not used by this adapter. The same adapter supports workspace-owned custom domains through /api/custom-domains; grant its IAM principal ses:CreateEmailIdentity, ses:GetEmailIdentity, ses:DeleteEmailIdentity, and ses:PutEmailIdentityMailFromAttributes in addition to the send permission. AWS credentials are never sent by clients or stored in ElecPostal.

For either adapter, set mail.relay.inboundHost to this service's public MX hostname. If DNS resolves a recipient domain to that host, ElecPostal stores the message directly in its local mailbox rather than handing it to the external delivery path.

Other delivery providers, including SES, are implemented as adapters behind the same outbound-delivery contract. Attachment IDs require a DysonFS byte source; until that is configured, enabled delivery rejects messages with attachments rather than dropping them.