Sendmail transport

The Sendmail transport hands the generated RFC 822 message off to the local sendmail (or compatible) binary by piping it to stdin. Functionally, this is the same mechanism used by PHP's mail() helper.

Usage

// CommonJS
const nodemailer = require("nodemailer");

const transporter = nodemailer.createTransport({
  sendmail: true, // enable Sendmail transport
});

Setting sendmail: true activates the transport. Nodemailer will try to locate the binary automatically (defaults to sendmail in your PATH). If necessary, you can point Nodemailer to a different binary with the path option (see below).

Transport options

Option	Type	Default	Description
path	String	'sendmail'	Absolute or relative path to the sendmail binary.
newline	'unix' / 'windows'	'unix'	Forces all line‑breaks in the generated message body to Unix (\n) or Windows (\r\n) style.
args	String[]	none	Additional sendmail CLI flags. Supplied flags completely replace Nodemailer's defaults except -i (do not treat a single dot on a line as message end) and the recipient list. Make sure to include every flag your installation requires—especially -f <from>.

When no custom args array is passed Nodemailer will execute

sendmail -i -f <from> <to…>

With args provided the command becomes

sendmail -i <args…> <to…>

Response

The info object that transporter.sendMail() yields contains only two properties—sendmail writes nothing to stdout/stderr:

• envelope – { from: 'address', to: ['address', …] }
• messageId – value of the generated Message‑ID header

Troubleshooting

If Nodemailer cannot find /usr/bin/sendmail (the default on most Unix systems) make sure the binary is installed and available on your PATH. Consult your distribution's documentation or the Computer Hope sendmail reference for installation instructions.

Examples

Pipe to a specific binary

const nodemailer = require("nodemailer");

const transporter = nodemailer.createTransport({
  sendmail: true,
  newline: "unix",
  path: "/usr/sbin/sendmail",
});

transporter.sendMail(
  {
    from: "sender@example.com",
    to: "recipient@example.com",
    subject: "Test message",
    text: "I hope this message gets delivered!",
  },
  (err, info) => {
    if (err) {
      console.error(err);
      return;
    }
    console.log(info.envelope);
    console.log(info.messageId);
  }
);

If you need to pass custom flags—for example, to override the envelope sender—include them via the args option:

const transporter = nodemailer.createTransport({
  sendmail: true,
  args: ["-f", "bounce@example.com"],
});