MailerSend

The MailerSend adapter calls the MailerSend Email API with plain fetch. Two quirks to know: MailerSend accepts exactly one reply-to address, and the message id comes back in the x-message-id response header rather than the body.

MailerSend

@opencoredev/email-sdk/mailersend

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Configure

Create an API token in the MailerSend dashboard and verify the domain you plan to send from.

import { createEmailClient } from "@opencoredev/email-sdk";
import { mailersend } from "@opencoredev/email-sdk/mailersend";

export const email = createEmailClient({
  adapters: [mailersend({ apiKey: process.env.MAILERSEND_API_KEY! })],
});

Send

MailerSend maps cc, bcc, headers, attachments (an attachment's contentId becomes MailerSend's id), and tags (values only). replyTo accepts a single address; two or more throw an EmailValidationError before any request. sendAt maps to send_at (a Unix timestamp in seconds), so MailerSend holds the message until then. It accepts at most 72 hours in the future.

const result = await email.send({
  from: "Acme <hello@acme.com>",
  to: [{ email: "user@example.com", name: "Ada" }],
  replyTo: "support@acme.com",
  subject: "Reset your Acme password",
  html: "<p>Click the link below to choose a new password.</p>",
  tags: [{ name: "type", value: "password-reset" }],
});

console.log(result.id); // MailerSend message id from the x-message-id header

The response id comes from the x-message-id response header, falling back to message_id or id in the body. Use it to look the send up in MailerSend's activity log.

Verify from the CLI

MAILERSEND_API_KEY="mlsn..." npx email-sdk doctor --adapter mailersend

MAILERSEND_API_KEY="mlsn..." npx email-sdk send \
  --adapter mailersend \
  --from "Acme <hello@acme.com>" \
  --to user@example.com \
  --subject "MailerSend smoke test" \
  --text "It works" \
  --dry-run

Drop --dry-run for one real send. The token, domain verification, and plan limits only prove themselves against the live API.