A transactional email API that sends through your own SMTP

A transactional email is triggered by a user's action and sent to that one person, as opposed to a marketing email sent to a whole list. People expect them quickly and reliably, so they need clear failure handling more than design tools.

• Password resets and email verification
• Order confirmations, shipping updates and receipts
• Booking and appointment reminders
• Account and security alerts
• Contact form notifications

Call it from your backend with the server key. The idempotency key means a retry after a timeout returns the first result instead of emailing the user twice.

import { NeuctraMailer, NeuctraMailerError } from "@neuctra/mailer";

try {
  await mailer.send(
    {
      to: user.email,
      subject: "Reset your password",
      html: `<p><a href="${resetUrl}">Choose a new password</a>. This link expires in 1 hour.</p>`,
      text: `Choose a new password: ${resetUrl}`,
    },
    // Retrying with the same key within 24 hours never sends a second email.
    { idempotencyKey: `password-reset-${token.id}` },
  );
} catch (err) {
  if (err instanceof NeuctraMailerError) {
    console.error(err.status, err.message, err.diagnosis?.title, err.requestId);
  }
}

• Temporary failures (a busy server, a dropped connection before sending) are retried up to 3 times, never in a way that could deliver twice
• Idempotency keys: a repeat within 24 hours returns the first result
• Every failure explains what went wrong and how to fix it, with provider-specific advice
• Email log of every send with the SMTP server's reply, never the email content
• Webhooks for sent, failed and bounced emails, signed so you can verify them
• Several SMTP accounts with automatic failover on paid plans

The test key (nm_test_...) checks and logs every request like a real one but delivers nothing, except to the test addresses you list, so you can still see emails arrive in your own inbox. Send to [email protected] to try your error handling. Test emails that aren't delivered don't count toward your plan.

Your emails go out from your own address and provider, so replies and sent folders stay where your team already works, and your sending reputation is yours. There is no per-email delivery charge from Neuctra Mailer: plans set monthly limits, starting with 1,000 emails a month free.