SMTP
Cloudflare-native SMTP
Connect directly from a Worker using Cloudflare TCP sockets instead of pushing mail through a separate Node server.
A tighter delivery path with fewer moving parts at the edge.
v1.3.3 • MIT licensed
Worker runtime email
Email for the Edge. Built for Cloudflare Workers.
worker-mailer keeps SMTP inside the Worker runtime, with a smaller transport layer, Bun-friendly workflows, and documentation that stays close to what the package actually ships.
Transport
SMTP
Direct delivery from Cloudflare Workers.
Optional
Queues
Move send work off the request path.
Typing
TypeScript
Hooks, DSN, attachments, and envelopes.
Current package surface
Direct Worker delivery
Cloudflare TCP sockets, SMTP auth modes, HTML/text bodies, and attachments.
Operational controls
Lifecycle hooks, DSN, custom SMTP errors, timeouts, and queue helpers.
Careful EmDash positioning
The project tracks the EmDash discussion, but this site does not pretend the integration contract is final.
Current surface area
A smaller mail stack, tuned for edge workloads.
worker-mailer focuses on the pieces that matter most in Workers: a lean SMTP client, solid types, and predictable delivery behavior.
TYPES
Type-safe envelopes
Typed transport and message options cover auth modes, DSN, attachments, headers, inline images, and queue payloads.
Safer refactors and faster editor feedback in Bun-first projects.
CID
HTML + inline assets
Send plain text, HTML, classic attachments, and inline CID images without bolting on a second mailer abstraction.
Useful for onboarding flows, invoices, and system notifications.
HOOKS
Hooks and observability
Lifecycle hooks and custom SMTP errors make it easier to trace connect, send, fail, and close events.
Helpful for retries, logging, and production diagnostics.
QUEUE
Queue-ready delivery
Optional Cloudflare Queues helpers let you move email work off the request path when throughput or latency matters.
Good fit for form spikes, batch sends, and webhook-heavy workloads.
DISCUSS
Watching EmDash carefully
The project is following the EmDash email-provider discussion, but this site only documents worker-mailer features that exist today.
No guessed plugin API, no speculative setup steps.
Example flows
Practical patterns without dumping code on the landing page.
The examples page now works like a catalog of real use cases. The full snippets stay in the documentation, where they belong.
smtp-basic.ts
Direct SMTP delivery
Connect once and send from a Worker when the request itself owns the delivery flow.
send-once.ts
One-off send
Use the static helper when you do not need to retain a transport instance between sends.
queue.ts
Queue consumer
Push email work into Cloudflare Queues to keep the request path thin.
inline-image.ts
HTML + CID image
Embed an inline image in the message body using a content ID attachment.
EmDash
Following the discussion without pretending the API is settled.
worker-mailer is relevant to the EmDash conversation because it already solves SMTP on Cloudflare Workers. That is different from claiming a final plugin contract or showing setup steps that have not been decided yet.
Concrete today
SMTP transport, queues, hooks, attachments, and TypeScript support.
Still open
Provider lifecycle, config conventions, and transport boundaries in EmDash.
How this site handles it
We link to the discussion and summarize the themes without fabricating examples.