SMTP Client

SMTP Client allows you to connect to and stream data to a SMTP server in the browser.

API

Installation: npm install emailjs-smtp-client

Create SmtpClient object with:

import SmtpClient from 'emailjs-smtp-client'
var client = new SmtpClient(host, port, options)

where

host is the hostname to connect to (defaults to "localhost")
port is the port to connect to
options is an optional options object (see below)

Connection options

The following connection options can be used with simplesmtp.connect:

useSecureTransport Boolean Set to true, to use encrypted connection
name String Client hostname for introducing itself to the server
auth Object Authentication options. Depends on the preferred authentication method
- user is the username for the user (also applies to OAuth2)
- pass is the password for the user if plain auth is used
- xoauth2 is the OAuth2 access token to be used instead of password. If both password and xoauth2 token are set, the token is preferred.
- authMethod String Force specific authentication method (eg. "PLAIN" for using AUTH PLAIN or "XOAUTH2" for AUTH XOAUTH2)
ca (optional) (only in conjunction with this TCPSocket shim) if you use TLS with forge, pin a PEM-encoded certificate as a string. Please refer to the tcp-socket documentation for more information!
disableEscaping Boolean If set to true, do not escape dots on the beginning of the lines
ignoreTLS – if set to true, do not issue STARTTLS even if the server supports it
requireTLS – if set to true, always use STARTTLS before authentication even if the host does not advertise it. If STARTTLS fails, do not try to authenticate the user
lmtp - if set to true use LMTP commands instead of SMTP commands

Default STARTTLS support is opportunistic – if the server advertises STARTTLS in EHLO response, the client tries to use it. If STARTTLS is not advertised, the clients sends passwords in the plain. You can use ignoreTLS and requireTLS to change this behavior by explicitly enabling or disabling STARTTLS usage.

XOAUTH2

To authenticate using XOAUTH2, use the following authentication config

var config = {
  auth: {
    user: 'username',
    xoauth2: 'access_token'
  }
}

See XOAUTH2 docs for more info.

Connection events

Once a connection is set up the following events can be listened to:

onidle - the connection to the SMTP server has been successfully set up and the client is waiting for an envelope. NB! this event is emitted multiple times - if an e-mail has been sent and the client has nothing to do, onidle is emitted again.
onready (failedRecipients) - the envelope is passed successfully to the server and a message stream can be started. The argument is an array of e-mail addresses not accepted as recipients by the server. If none of the recipient addresses is accepted, onerror is emitted instead.
ondone (success) - the message was sent
onerror (err) - An error occurred. The connection will be closed shortly afterwards, so expect an onclose event as well
onclose (isError) - connection to the client is closed. If isError is true, the connection is closed because of an error

Example:

client.onidle = function(){
  console.log("Connection has been established");
  // this event will be called again once a message has been sent
  // so do not just initiate a new message here, as infinite loops might occur
}

Sending an envelope

When an onidle event is emitted, an envelope object can be sent to the server. This includes a string from and a single string or an array of strings for to property.

Envelope can be sent with client.useEnvelope(envelope)

// run only once as 'idle' is emitted again after message delivery
var alreadySending = false;

client.onidle = function(){
  if(alreadySending) return

  alreadySending = true
  client.useEnvelope({
    from: "me@example.com",
    to: ["receiver1@example.com", "receiver2@example.com"]
  })
}

The to part of the envelope must include all recipients from To:, Cc: and Bcc: fields.

If envelope setup up fails, an error is emitted. If only some (not all) recipients are not accepted, the mail can still be sent. An onready event is emitted when the server has accepted the from and at least one to address.

client.onready = function(failedRecipients){
  if(failedRecipients.length){
    console.log("The following addresses were rejected: ", failedRecipients)
  }
  // start transfering the e-mail
}

Sending a message

When onready event is emitted, it is possible to start sending mail. To do this you can send the message with client.send calls (you also need to call client.end() once the message is completed).

send method returns the state of the downstream buffer - if it returns true, it is safe to send more data, otherwise you should (but don't have to) wait for the ondrain event before you send more data.

NB! you do not have to escape the dots in the beginning of the lines by yourself (unless you specificly define so with disableEscaping option).

client.onready = function(){
  client.send("Subject: test\r\n");
  client.send("\r\n");
  client.send("Message body");
  client.end();
}

Once the message is delivered an ondone event is emitted. The event has an parameter which indicates if the message was accepted by the server (true) or not (false).

client.ondone = function(success){
  if(success){
    console.log("The message was transmitted successfully");
  }
}

Closing the connection

Once you have done sending messages and do not want to keep the connection open, you can gracefully close the connection with client.quit() or non-gracefully (if you just want to shut down the connection and do not care for the server) with client.close().

If you run quit or close in the ondone event, then the next onidle is never called.

Quirks

STARTTLS is currently not supported
Only PLAIN, USER and XOAUTH2 authentication mechanisms are supported. XOAUTH2 expects a ready to use access token, no tokens are generated automatically.

License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.