Bulletproof email queue on top of NodeMailer with support of multiple clusters and servers setup. 

📮 Email queue extending NodeMailer with multi SMTP transports and horizontally scaled apps support

dr.dimitru

mail-time

Bulletproof email queue on top of NodeMailer with support of multiple clusters and servers setup

    console.info.call(console, '[DEBUG] [mail-time]', `${new Date}`, ...args);

  console.error.call(console, '[ERROR] [mail-time]', `${new Date}`, ...args);

    _logError('[mongoErrorHandler]:', error);

  if (!(typeof a === 'object' && typeof b === 'object')) {

  if (a instanceof Date && b instanceof Date) {

    for (i = _a.length - 1; i >= 0; i--) {

      for (j = _b.length - 1; j >= 0; j--) {

  if (typeof a === 'object' && typeof b === 'object') {

    for (i = akeys.length - 1; i >= 0; i--) {

      if (!hasOwnProperty.call(b, akeys[i])) {

      if (!equals(a[akeys[i]], b[akeys[i]])) {

      throw new Error('[mail-time] [sendMail] [___compileMailOpts] transport not available or misconfiguration is in place!');

    if (transport._options && typeof transport._options === 'object' && transport._options !== null && transport._options.mailOptions) {

      _mailOpts = merge(_mailOpts, transport._options.mailOptions);

    if (transport.options && typeof transport.options === 'object' && transport.options !== null && transport.options.mailOptions) {

      _mailOpts = merge(_mailOpts, transport.options.mailOptions);

    for (let i = 0; i < task.mailOptions.length; i++) {

        if (task.mailOptions.length > 1) {

          _mailOpts.html += this.___render(this.concatDelimiter, task.mailOptions[i]) + this.___render(task.mailOptions[i].html, task.mailOptions[i]);

          _mailOpts.html = this.___render(task.mailOptions[i].html, task.mailOptions[i]);

          _mailOpts.text += '\r\n' + this.___render(task.mailOptions[i].text, task.mailOptions[i]);

          _mailOpts.text = this.___render(task.mailOptions[i].text, task.mailOptions[i]);

      _mailOpts = merge(_mailOpts, task.mailOptions[i]);

    if (_mailOpts.html && (task.template || this.template)) {

      _mailOpts.html = this.___render((task.template || this.template), _mailOpts);

      _mailOpts.subject = task.concatSubject || this.concatSubject || _mailOpts.subject;

      _mailOpts.from = this.from(transport);

   @param ready {Function} - See JoSk NPM package

    const cursor = this.collection.find({

          $lt: new Date(Date.now() - (this.zombieTime * 2))

    cursor.count((countError, count) => {

        _logError('[___send] [count] [countError]', countError);

  "description": "Bulletproof email queue on top of NodeMailer with support of multiple clusters and servers setup",

    "url": "git://github.com/VeliovGroup/Mail-Time.git"

    "url": "https://github.com/VeliovGroup/Mail-Time/issues"

  "homepage": "https://github.com/VeliovGroup/Mail-Time",

  "author": "dr.dimitru (https://veliovgroup.com)",

    "nodemailer-direct-transport": "^3.3.2"

Micro-service package for mail queue, with *Server* and *Client* API.

Build on top of [`nodemailer`](https://github.com/nodemailer/nodemailer) package.

Every `MailTime` instance can be configured to be a *Server* or *Client*.

Main difference of *Server* from *Client* - *Server* handles queue and actually sends email.

While *Client* is only put emails into the queue.

- [How it works?](https://github.com/VeliovGroup/Mail-Time#how-it-works)

  - [With single SMTP](https://github.com/VeliovGroup/Mail-Time#single-point-of-failure)

  - [With multiple SMTP](https://github.com/VeliovGroup/Mail-Time#multiple-smtp-providers)

  - [As Micro-Service](https://github.com/VeliovGroup/Mail-Time#cluster-issue)

- [Features](https://github.com/VeliovGroup/Mail-Time#features)

- [Installation](https://github.com/VeliovGroup/Mail-Time#installation)

- [Meteor.js Installation](https://github.com/VeliovGroup/Mail-Time#installation--import-via-npm): as [NPM Package](https://www.npmjs.com/package/mail-time)

- [Meteor.js Installation](https://github.com/VeliovGroup/Mail-Time#installation--import-via-atmosphere): as [Atmosphere package](https://atmospherejs.com/ostrio/mailer)

- [Usage example](https://github.com/VeliovGroup/Mail-Time#basic-usage)

- [API](https://github.com/VeliovGroup/Mail-Time#api)

  - [*Constructor*](https://github.com/VeliovGroup/Mail-Time#new-mailtimeopts-constructor)

  - [`.send()`](https://github.com/VeliovGroup/Mail-Time#sendmailopts--callback)

  - [Default Template](https://github.com/VeliovGroup/Mail-Time#static-mailtimetemplate)

- [Custom Templates](https://github.com/VeliovGroup/Mail-Time#template-example)

- [~92% tests coverage](https://github.com/VeliovGroup/Mail-Time#testing)

- 📦 Two simple dependencies, written from scratch for top performance;

- 🏢 Synchronize email queue across multiple servers;

- 💪 Bulletproof design, built-in retries.

Issue - classic solution with the single point of failure:

|----------------|         |------|         |------------------|

|  Other mailer  | ------> | SMTP | ------> |  ^_^ Happy user  |

The scheme above will work as long as SMTP service is available

or connection between your server and SMPT is up. Once network

failure occurs or SMTP service is down - users won't be happy

|----------------|  \ /    |------|         |------------------|

|  Other mailer  | --X---> | SMTP | ------> | 0_o Disappointed |

|----------------|  / \    |------|         |------------------|

                     ^- email lost in vain

Single SMTP solution may work in case of network or other failures

As long as MailTime has not received confirmation what email is sent

it will keep the letter in the queue and retry to send it again

|----------------|    /    |------|         |------------------|

|   Mail Time    | --X---> | SMTP | ------> |  ^_^ Happy user  |

|---^------------|  /      |------|         |------^-----------|

     \-------------/ ^- We will try later         /

      \- put it back into queue                  /

       \----------Once connection is back ------/

Backup scheme with multiple SMTP providers

                   /    \--- Retry with next provider

|----------------|/        |--------|         |------------------|

|   Mail Time    | ---X--> | SMTP 2 |      /->|  ^_^ Happy user  |

|----------------|\   ^    |--------|     /   |------------------|

                   \  \--- Retry         /

                    \      |--------|   /

Let's say you have an app which is growing fast. At some point, you've decided to create a "Cluster" of servers to balance the load and add durability layer.

Also, your application has scheduled emails, for example, once a day with recent news. While you have had single server emails was sent by some daily interval. So, after you made a "Cluster" of servers - each server has its own timer and going to send a daily email to our user. In such case - users will receive 3 emails, sounds not okay.

| |----------|     |----------|     |----------|  | |       | |=Micro-service=|   |--------|

| |   App    |     |   App    |     |   App    |  | |       | |               |-->| SMTP 1 |------\

| | Server 1 |     | Server 2 |     | Server 3 |  | |    <--------            |   |--------|       \

| |-----\----|     |----\-----|     |----\-----|  | |    -------->            |                |-------------|

|        \---------------\----------------\---------->      | |               |   |--------|   |     ^_^     |

| runs Mail Time as a Client which only puts      | |       | |               |   |--------|   |-------------|

| emails into the queue. Aside to "App Servers"   | |       | |               |                    /

		@@ -225,2 +225,6 @@ const JoSk = require('josk');

		if (!transport) {
		throw new Error('[mail-time] [sendMail] [___compileMailOpts] transport not available or misconfiguration is in place!');
		}

		if (transport._options && typeof transport._options === 'object' && transport._options !== null && transport._options.mailOptions) {
		@@ -227,0 +231,0 @@ _mailOpts = merge(_mailOpts, transport._options.mailOptions);

		{
		"name": "mail-time",
		"version": "1.2.3",
		"version": "1.2.4",
		"description": "Bulletproof email queue on top of NodeMailer with support of multiple clusters and servers setup",
		@@ -52,13 +52,13 @@ "main": "index.js",
		"deepmerge": "^4.2.2",
		"josk": "^2.2.3"
		"josk": "^2.2.5"
		},
		"devDependencies": {
		"bson": "^4.0.3",
		"bson": "^4.0.4",
		"bson-ext": "^2.0.3",
		"chai": "^4.2.0",
		"mocha": "^7.1.0",
		"mongodb": "^3.5.4",
		"nodemailer": "^6.4.4",
		"mocha": "^7.1.2",
		"mongodb": "^3.5.7",
		"nodemailer": "^6.4.6",
		"nodemailer-direct-transport": "^3.3.2"
		}
		}

		@@ -7,2 +7,6 @@ # MailTime

		<a href="https://ostr.io">
		<img src="https://ostr.io/apple-touch-icon-60x60.png" height="38">
		</a>

		Micro-service package for mail queue, with Server and Client API.
		@@ -9,0 +13,0 @@ Build on top of [`nodemailer`](https://github.com/nodemailer/nodemailer) package.

Improved metrics

Dependency changes