Overview

A custom Mail-listener5 library for node.js. Get notification when new email arrived to inbox or when message metadata (e.g. flags) changes externally. Uses IMAP protocol. Allow to choice if you prefer save attachment file on storage.

Version Notes

This package has several improvements and fixes over the mail-listener2 & mail-listener4. Most of the improvements are designed to improve security & usability, plus avoid deprecation warnings. The previous mail-listener packages used a now-deprecated version of MailParser and unsafe buffer constructors (see change notes below).

This package uses the simpleParser function in NodeMailer. This parser is easier to implement & provides a Mail object from which any needed attributes can be extracted. However, it is more resource-intensive when it comes to larger emails, as attachments are not handled as streams, but rather are buffered in memory. In a future version, I plan to reintroduce the ability to stream attachments directly (rather than buffering them) so that larger attachments can be processed with fewer resources.

Change notes:

• v2.1.2:
  • Added "autotls" option as documented in node-imap. (Thanks @MorphedAU!)
  • Updated dependencies.
• v2.1.0:
  • Updating dependencies to new versions (fixes Issue #35, Issue #36 and Snyk security findings).
  • Improvements to email attribute handling as per the suggestions in Issue #28.
  • Error handling fixes (fix for Issue #33).
• Changes from mail-listener4:
  • Updating dependencies to newer versions, with security enhancements, etc. The previous mail-listeners all used now-deprecated versions of dependencies, many of which posed security problems as they used unsafe Buffer constructors (e.g. new Buffer() - see https://nodejs.org/en/docs/guides/buffer-constructor-deprecation/).
  • Updating code to use ES6 classes. The previous version used util.inherits(), which is now discouraged (see https://nodejs.org/dist/latest-v10.x/docs/api/util.html#util_util_inherits_constructor_superconstructor).
  • Updating code to use lexical variable declarations where appropriate.
  • Updating code to use ES6 arrow functions within methods where appropriate.
  • Updating test.js to use environment variables for credentials, etc (see new Testing section below).

We are using these libraries: node-imap, mailparser.

Heavily inspired by mail-listener2 and mail-listener5.

NOTE: This version is designed to work with & tested on NodeJS v 18.13.0 LTS, the most recent LTS version as at January 2023. It might not work on older versions of Node.

Planned Future Improvements

Whilst this package is confirmed to work, the ability to stream attachments (present in the older versions of mail-listener) has been taken out, mainly because the MailParser library has changed significantly & a substantial amount of refactoring is required in order to allow the safe streaming of attachments (which may contain untrusted content).

A future version will reintroduce this capability once the refactoring is complete. That version will allow attachments to be streamed directly to functions. At present, attachments are either saved to a file for later processing (if that option is selected) or an 'attachment' event is emitted, which contains a Buffer with the attachment content. This Buffer can then be processed as needed.

Known issues

Some email attachments will not be processed properly, but will instead be saved into a single file in the attachments directory called "Undefined". This was raised in Issue #32. The issue does not occur with all attachments; the majority of attachments tested were saved properly. This problem is under investigation and will be fixed in a future release.

Use

Install

npm install mail-listener5-custom

JavaScript Code:

var { MailListener } = require("mail-listener5-custom");   // NOTE: A FUTURE VERSION (release date TBA) will not require ES6 destructuring or referring to the class after the require statement (i.e. require('mail-listener5-custom').MailListener). At this stage, this is necessary because index.js exports the MailListener class as a property of module.exports.

var mailListener = new MailListener({
  username: "imap-username",
  password: "imap-password",
  host: "imap-host",
  port: 993, // imap port
  tls: true,
  connTimeout: 10000, // Default by node-imap
  authTimeout: 5000, // Default by node-imap,
  debug: console.log, // Or your custom function with only one incoming argument. Default: null
  autotls: 'never', // default by node-imap
  tlsOptions: { rejectUnauthorized: false },
  mailbox: "INBOX", // mailbox to monitor
  searchFilter: ["ALL"], // the search filter being used after an IDLE notification has been retrieved
  markSeen: true, // all fetched email will be marked as seen and not fetched next time
  fetchUnreadOnStart: true, // use it only if you want to get all unread email on lib start. Default is `false`,
  attachments: true, // download attachments as they are encountered to the project directory
  saveAttachmentsOnStorage: true, // Allow to choice if you want to save the attachment file on storage
  attachmentOptions: { directory: "attachments/" } // specify a download directory for attachments
});

mailListener.start(); // start listening

// stop listening
//mailListener.stop();

mailListener.on("server:connected", function(){
  console.log("imapConnected");
});

mailListener.on("mailbox", function(mailbox){
  console.log("Total number of mails: ", mailbox.messages.total); // this field in mailbox gives the total number of emails
});

mailListener.on("server:disconnected", function(){
  console.log("imapDisconnected");
});

mailListener.on("error", function(err){
  console.log(err);
});

mailListener.on("headers", function(headers, seqno){
  // do something with mail headers
});

mailListener.on("body", function(body, seqno){
  // do something with mail body
})

mailListener.on("attachment", function(attachment, path, seqno){
  // do something with attachment
});

mailListener.on("mail", function(mail, seqno) {
  // do something with the whole email as a single object
})

// it's possible to access imap object from node-imap library for performing additional actions. E.x.
mailListener.imap.move(:msguids, :mailboxes, function(){})

That's easy!

Attachments

Attachments in this version are buffered. This feature is based on how mailparser's simpleParser function handles attachments. Setting attachments: true will download attachments as buffer objects by default to the project directory. A specific download directory may be specified by setting attachmentOptions: { directory: "attachments/"}. The "attachment" event will be fired every time an attachment is encountered.

Testing

A test script is available at test.js. Before using the test script, it is necessary to set the following environment variables:

• IMAPUSER - IMAP account username.
• IMAPPASS - IMAP account password.
• IMAPHOST - IMAP server hostname (e.g. imap.example.com).

The test script assumes that the IMAP host supports TLS and that the port is the usual 993. These values can be changed in test.js if necessary.

To run the test script, simply execute:

export IMAPUSER='[email protected]' IMAPPASS='password' IMAPHOST='imap.example.com'; node test.js

License

MIT