email-notifier

Cloudflare Email Worker that, for each incoming email, forwards it to another mail server and posts a Discord notification chosen by the recipient's username.

Mail to {username}@your-domain (e.g. user1@gophercon.jp) is forwarded to {username}@FORWARD_EMAIL_DOMAIN and posted as a Discord embed to the webhook mapped to {username}. Usernames with no mapping are forwarded only (no error).

Domain-agnostic; single runtime dependency (postal-mime).

How it works

email() (src/index.ts) starts message.forward() without awaiting (concurrent with the notification), looks up the webhook for the username — parsing DISCORD_WEBHOOK_MAP once per instance — posts the email as a Discord embed with the body trimmed to Discord's limits, then awaits the forward. Notification errors are logged and swallowed so forwarding is never affected.

Configuration

Two values, read as Workers secrets in production and dev vars locally:

Name	Description
DISCORD_WEBHOOK_MAP	JSON object mapping username → Discord webhook URL.
FORWARD_EMAIL_DOMAIN	Domain incoming mail is forwarded to.

Both live in a git-ignored .env.yaml (see .env.yaml.example):

cp .env.yaml.example .env.yaml   # then edit
bun run gen:dev-vars             # -> .dev.vars for local dev

For production the same .env.yaml is stored as one GitHub secret and pushed to the Worker by the deploy workflow (see Deployment); no manual wrangler secret put is needed.

Development

Toolchain (bun, node) is pinned in mise.toml; installs enforce a 3-day release cooldown (bunfig.toml) for supply-chain safety.

mise install        # pinned bun/node (optional)
bun install
bun run gen         # gen:cf-types + gen:dev-vars
bun run dev         # vite dev, loads .dev.vars
bun run typecheck   # tsc --noEmit
bun run test        # vitest (Workers runtime)
bun run build       # vite build

Deploys happen in CI on merge to main (see Deployment); there is no local deploy script.

Deployment

Merging to main deploys via .github/workflows/deploy.yml.

Set these repository secrets (Settings → Secrets and variables → Actions):

Secret	Value
CLOUDFLARE_API_TOKEN	Cloudflare token with Workers edit permission.
ENV_YAML	The full contents of your .env.yaml (same file used locally).

Production and local dev share one .env.yaml; change a webhook or the forward domain by editing ENV_YAML and re-running the deploy.

One-time setup outside CI: create the API token, and route incoming mail to this Worker in the Cloudflare dashboard (Email → Email Routing → Email Workers).