Plugins

Five slots are drop-in catalogs under plugins/. Cloudflare Workers cannot load native .so files, so a plugin is a JSON or image file compiled into the Worker. You pick the active id in config/mail.json (or with env vars). Unused chrome is omitted.

Slot	Drop files in	Select with	Runtime override
Provider	plugins/providers/*.json	plugins.provider	MAIL_PROVIDER
Features	plugins/features/*.json	features.* (false hides it)	—
Theme	plugins/themes/*.json	plugins.theme	MAIL_THEME
Layout	plugins/layouts/*.json	plugins.layout	MAIL_LAYOUT
Logo	plugins/logos/*	plugins.logo	MAIL_LOGO
Config	config/overlays/*.json	omit unused keys	MAIL_CONFIG_JSON

GET /api/health lists the compiled catalog under available and the active ids under plugins.

Provider

Bundled: brevo · resend · sendgrid · mailgun · postmark · mailersend · smtp2go · sparkpost.

JSON registers id, label, secret names, and whether a sending domain is required. A new HTTP ESP still needs a send adapter in Rust (src/plugins/provider.rs).

Features

Drop JSON under plugins/features/. Each file is a toggle in features.* — set it to false to hide that capability. Bundled: markdown · history · attachments.

Theme

Drop a palette JSON — no Rust change. Bundled: forest · midnight · ocean · paper · rose · slate · aurora · sunset · nord.

Unknown ids fall back to forest. brand.* color keys override individual tokens.

Example plugins/themes/nord.json:

{
  "id": "nord",
  "label": "Nord",
  "aliases": ["polar"],
  "accent": "#5e81ac",
  "accentDeep": "#2e3440",
  "accentSoft": "#eceff4",
  "ink": "#2e3440",
  "muted": "#4c566a",
  "paper": "#eceff4",
  "line": "#d8dee9",
  "heroFrom": "#5e81ac",
  "heroTo": "#3b4252",
  "headerText": "#eceff4"
}

Layout

JSON sets header style, body padding, and card shadow — no Rust change for those knobs. Bundled: card · minimal · banner · digest · compact.

{
  "id": "compact",
  "label": "Compact",
  "headerStyle": "plain",
  "bodyPadding": "12px 16px 12px",
  "cardShadow": "none"
}

headerStyle is plain, gradient, or none.

Logo

plugins.logo	What you see
auto	Image if a path/file exists; otherwise a monogram from site.brandName; otherwise omit
image	Configured or first file in plugins/logos/; monogram if missing
monogram	Letter mark only
none	No mark

Files in plugins/logos/ are copied to /plugins/logos/<filename> at build. Point site.logoPath at that URL, or leave it empty to use the first file.

Config overlays

JSON in config/overlays/ is deep-merged onto mail.json at compile time (overlay wins; null deletes a key). For a runtime overlay without rebuilding:

MAIL_CONFIG_JSON='{"plugins":{"theme":"nord","logo":"monogram"}}'

Slot env vars (MAIL_THEME, …) are applied after that overlay.

After adding a file

cargo test --lib
npm run deploy
# or: docker compose build

JSON/logo files need a rebuild. Switching the active id with MAIL_* does not.