mailerEmail for Node.js, with a reliability layer

SMTP, sendmail, MIME and DKIM of its own, eighteen HTTP providers and JMAP, with failover, retries, rate limits and idempotency around them, and verified webhooks into one model of delivery events. Zero dependencies. On top, a persistent queue with templates of your engine and an audit of every state.

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Transports

Compared with alternatives

✉️

SMTP of its own

Pooling, STARTTLS, AUTH PLAIN, LOGIN and OAuth 2.0, PIPELINING, SIZE, DSN and SMTPUTF8, on node:net and node:tls, through an HTTP CONNECT proxy if you need one; and sendmail. Certificates are verified, and credentials never cross plain text.

SMTP transport

🔏

MIME and DKIM

createMessage validates addresses, headers and attachments, and takes List-Unsubscribe with one-click. The MIME writes IDN domains as punycode, keeps the Bcc out of the headers, carries inline images and iCalendar invitations, and is DKIM-signed with RSA or Ed25519.

Composing messages

🌐

Eighteen HTTP providers and JMAP

Amazon SES v2, Resend, SendGrid, Mailgun, Postmark, Brevo, Mailjet, MailerSend, SparkPost and nine more on fetch, and JMAP. One Transport contract and one Receipt with classified errors: swap the provider, keep the messages.

Choose a transport

🧩

Decorators around any transport

A pool with strategies and failover, retries with backoff, jitter and Retry-After, a circuit breaker, token-bucket rate limits, idempotency keys, hooks, mirroring, OpenTelemetry spans and metrics, logs through your pino logger, and a mock for tests.

Pool, retry, breaker

🪶

Zero dependencies

Built on node:* and fetch. The OpenTelemetry providers, the logger, React Email's render, your template engine and BullMQ come from your application. Node.js 22+, tested on Bun and Deno, CommonJS with ESM imports, hand-written types.

API

🧾

The reliability layer

A queue on BullMQ or a store of yours, whose workers render your templates, fail a permanent failure at once and retry a temporary one after Retry-After; the webhooks of fifteen providers in one model of delivery events; an audit of every state. None of the fourteen libraries compared has them.

The queue

Status

The transport layer is here, ported from upyo 0.7.0 (MIT), with what nodemailer, unemail and sently did better ported in 1.1: one package, with a subpath per transport and decorator. Delivery events are here too, and, from 1.2, the queue, templates and the audit. See Why @alexify/mailer? for the plan.

A quick look

const { createMessage } = require('@alexify/mailer');
const { SmtpTransport } = require('@alexify/mailer/smtp');
const { createRetryTransport } = require('@alexify/mailer/retry');

const transport = createRetryTransport(
  new SmtpTransport({
    host: 'smtp.example.com',
    port: 587,
    auth: { user: 'user@example.com', pass: 'secret' },
  }),
  { maxAttempts: 3 },
);

const receipt = await transport.send(
  createMessage({
    from: 'Alex <alex@example.com>',
    to: 'bob@example.net',
    subject: 'Your invoice',
    content: { text: 'Attached.', html: '<p>Attached.</p>' },
  }),
);

if (receipt.successful) console.log(receipt.messageId);
else console.error(receipt.errorMessages, receipt.retryable);