smtp-protocol

implements the smtp protocol for clients and servers

npm install smtp-protocol
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smtp-protocol

write smtp clients and servers

This module does not relay any messages or perform disk I/O by itself.

build status

examples

server

var smtp = require('smtp-protocol');

var server = smtp.createServer(function (req) {
    req.on('to', function (to, ack) {
        var domain = to.split('@')[1] || 'localhost';
        if (domain === 'localhost') ack.accept()
        else ack.reject()
    });

    req.on('message', function (stream, ack) {
        console.log('from: ' + req.from);
        console.log('to: ' + req.to);

        stream.pipe(process.stdout, { end : false });
        ack.accept();
    });
});

server.listen(9025);

usage:

$ node example/server.js

elsewhere:

$ nc localhost 9025
250 beep
helo
250 
mail from: <beep@localhost>
250 
rcpt to: <boop@localhost>
250 
data
354 
Beep boop.
I am a computer.
.
250 
quit
221 Bye!

meanwhile:

from: beep@localhost
to: boop@localhost
Beep boop.
I am a computer.

client

var smtp = require('smtp-protocol');
var fs = require('fs');

smtp.connect('localhost', 9025, function (mail) {
    mail.helo('example.com');
    mail.from('substack@example.com');
    mail.to('root@example.com');
    mail.data();
    fs.createReadStream('/etc/issue').pipe(mail.message());
    mail.quit();
});

output:

$ node example/client.js
[ 'beep ESMTP Postfix (Ubuntu)' ]
{ helo: 250,
  from: 250,
  to: 250,
  data: 354,
  message: 250,
  quit: 221 }

server methods

var smtp = require('smtp-protocol')

smtp.createServer(domain=os.hostname(), cb)

Return a new net.Server so you can .listen() on a port.

cb(req) fires for new connection. See the "requests" section below.

server requests

events

Every event that can

Every acknowledgeable event except "message" will implicitly call ack.accept() if no listeners are registered.

If there are any listeners for an acknowledgeable event, exactly one listener MUST call either ack.accept() or ack.reject().

'command', cmd, r

This event fires for every smtp command. cmd has the command name as cmd.name and the cmd.data as the command data.

If you want to override the default behavior for a command, call r.preventDefault(), then call r.write(code, data) to write a response and r.next() when the next command should be processed.

'greeting', cmd, ack

Emitted when HELO, EHLO, or LHLO commands are received.

Read the name of the command with cmd.greeting. Read the optional hostname parameter with cmd.hostname.

'from', from, ack

Emitted when the MAIL FROM: command is received.

from is the email address of the sender as a string.

'to', to, ack

Emitted when the RCPT TO: command is received.

to is the email address of the recipient as a string.

'message', stream, ack

Emitted when the DATA command is received.

If the message request is accepted, the message body will be streamed through stream.

This event has no implicit ack.accept() when there are no listeners.

'received', ack

Emitted when the body after the DATA command finishes.

'reset'

Emitted when the connection is reset from a RSET command.

'quit'

Emitted when the connection is closed from a QUIT command.

'tls'

Emitted when the connection is upgraded to TLS by the client.

properties

req.from

The email address of the sender as a string.

req.fromExt

Extended sender data if sent as a string.

req.to

The email address of the recipient as a string.

req.toExt

Extended recipient data if sent as a string.

req.greeting

The greeting command. One of 'helo', 'ehlo', or 'lhlo'.

req.hostname

The hostname specified in the greeting.

server acknowledgements

Many request events have a trailing ack parameter.

If there are any listeners for an acknowledgeable event, exactly one listener MUST call either ack.accept() or ack.reject().

Consult this handy list of SMTP codes for which codes to use in acknowledgement responses.

ack.accept(code=250, message)

Accept the command. Internal staged state modifications from the command are executed.

ack.reject(code, message)

Reject the command. Any staged state modifications from the command are discarded.

client methods

For all client methods, cb(err, code, lines) fires with the server response.

var stream = smtp.connect(host='localhost', port=25, options={}, cb)

Create a new SMTP client connection.

host, port, options and cb are detected by their types in the arguments array so they may be in any order. cb(client) fires when the connection is ready.

You can use unix sockets by supplying a string argument that matches /^[.\/]/.

Alternatively supply your own stream as opts.stream (the stream must already be connected).

To make a connection using TLS, set opts.tls to true (for more control you can also assign options to pass through to tls.connect.) You can also upgrade the connection to TLS at any time by calling client.startTLS().

By default, connections to unauthorized servers will be closed and the error will be emitted as an 'error' event on the stream object but you can provide your own authorization logic by doing:

stream.on('secure', function (ack) {
    if (...) ack.accept()
    else ack.reject()
})

client.helo(hostname, cb)

Greet the server with the hostname string.

cb(err, code, lines) fires with the server response.

client.from(addr, ext=undefined, cb)

Set the sender to the email address addr with optional extension data ext.

cb(err, code, lines) fires with the server response.

client.to(addr, ext=undefined, cb)

Set the recipient to the email address addr with optional extension data ext.

cb(err, code, lines) fires with the server response.

client.data(cb)

Tell the server that we are about to transmit data.

cb(err, code, lines) fires with the server response.

var stream = client.message(cb)

Return a writable stream to send data to the server in a message body. For example, you could do:

fs.createReadStream('foo.txt').pipe(client.message());

cb(err, code, lines) fires with the server response.

client.quit(cb)

Ask the server to sever the connection.

cb(err, code, lines) fires with the server response.

client.reset(cb)

Ask the server to reset the connection.

cb(err, code, lines) fires with the server response.

client.startTLS(opts={}, cb)

Upgrade the current connection to TLS with opts passed through to tls.connect(opts).

If opts.servername isn't given, its value will be taken from the HELO/EHLO hostname value because otherwise the TLS library will complain about how the certificate name doesn't match.

You'll probably want to pass in the opts.ca here as well to satisfy the TLS machinery.

client events

'greeting', code, lines

Fired when the stream initializes. This should be the first message that the server sends.

'tls', clearTextStream

When the connection is upgraded to TLS, this event fires.

install

With npm do:

npm install smtp-protocol

license

MIT

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