Send Transactional Email with SMTP

The SMTP password is a Lumail API token, not your Lumail account password.

1. Open your Lumail organization.
2. Go to Settings -> API Tokens.
3. Click Generate Token.
4. Name it clearly, for example Production SMTP.
5. Copy the token immediately and store it in your application's secret manager.

The token starts with lum_.

Step 3 - Configure Your SMTP Client

Use these settings in your external application:

The username is used as a label in SMTP logs. The password is what authenticates the request.

Supabase Auth Example

For Supabase Auth custom SMTP, configure:

Host: smtp.lumail.io
Port: 587
Security: STARTTLS
Username: your-org-slug
Password: lum_your_api_token
Sender email: [email protected]

Use the same sender address in Supabase email templates. The sender domain must already be verified in Lumail.

Nodemailer Example

import nodemailer from "nodemailer";

const transport = nodemailer.createTransport({
  host: "smtp.lumail.io",
  port: 587,
  secure: false,
  requireTLS: true,
  auth: {
    user: "your-org-slug",
    pass: process.env.LUMAIL_API_TOKEN,
  },
});

await transport.sendMail({
  from: "Auth Team <[email protected]>",
  to: "[email protected]",
  subject: "Your login code",
  text: "Your login code is 123456.",
});

Test the Connection

You can test the SMTP endpoint with swaks:

swaks \
  --server smtp.lumail.io \
  --port 587 \
  --tls \
  --auth LOGIN \
  --auth-user your-org-slug \
  --auth-password lum_your_api_token \
  --from [email protected] \
  --to [email protected] \
  --header "Subject: Lumail SMTP test" \
  --body "This email was sent through Lumail SMTP."

A successful response ends with:

250 Queued 1 message(s)

That means Lumail accepted the email and queued it on the transactional priority lane. Final inbox placement still depends on the receiving mailbox and downstream delivery provider.

Message Behavior

Send one SMTP message per recipient. If your application needs bulk sending, use Lumail campaigns or workflows instead.

Troubleshooting

If your provider asks for SSL/TLS on port 465, choose STARTTLS on port 587 instead. Lumail's SMTP endpoint is exposed on 587.

Related Documentation

• SMTP Endpoint Reference - Connection settings and response codes
• Create an API Token - Generate the token used as the SMTP password
• Email Domains - Verify the domain used in your From address
• Send Transactional Email API - Prefer this API when your application supports HTTP