The problem

We know emails are VERY HARD to develop from scratch. Even if there are tools like Maiject, SendPulse, MailerSend, Stripo.email etc (maybe with a good drag-n-drop UI) sometimes you find yourself in one of the following cases:

• you need to produce some html files using layouts and partials for different languages, passing them to a backend witch add maybe some data coming from itself (or another service) and fills your html files with its template engine.
• backend of your company deploy email using with a custom service that use Amazon SES.
• previous providers are not able to customize some parts. For example css rule. Or to do this is very complicated.
• coming from email-foundation-template and you want to try a different tool with advantages (please read below about features), or you need to use different template engine with more power (see Eta.js).
• having complete control of development without use any Saas is mandatory.

This solution

marilena wants to mix up MJML, an optional template engine for variables and a web server, to create a tool able to generate emails with a simple flow and one command. Please keep in mind that Maiject, SendPulse, MailerSend, Stripo.email etc maybe can be already perfect for your purpose.

🚀 Usage

Install (require node >=18)

npm i marilena

Setup

marilena provides a command witch generate a small but working example with eta.js, variables, layout and partials. You can generate an example with:

npx marilena --create-example

and change package.json like:

"type": "module",
"scripts": {
  "start": "marilena --server --project example/marilena.config.mjs",
  "build": "marilena --build --project example/marilena.config.mjs",
},

Setup (manual)

If you fails to generate the example or you want to build a project from 0 you need to crete marilena.config.mjs file in the root of your project. Please check below the fields since any of these are required.

import path from "node:path";
// you can leverage your IDE's intellisense with jsdoc type hints
/** @type {import('marilena/dist/src/types').UserConfig} */
export default {
  inputFolder: "./input",
  outputFolder: "./output",
  textVersion: (emailName, locale) => `${emailName}_text_version-${locale}.txt`,
  htmlVersion: (emailName, locale) => `${emailName}-custom.html`,
  locales: ["it", "en"],
  templateOptions: {
    engine: "eta",
    prepareEngine: (eta) => {
      eta.configure({
        views: path.join(process.cwd(), "playground/input"),
      });
    },
  },
  mjmlParsingOptions: {
    keepComments: false,
  },
};

Edit you package.json. By default marilena try to find config in the root of your project. If you put the config in a different path, you need to pass --project argument in the scripts

"scripts": {
  "start": "marilena --server",
  "build": "marilena --build",
},

create a file structures based on your config. Please remember that each email template requires index.html as name, and variables are loaded only from variables.json or variables.yml. Yes you can use both (result will be an union of two).

project
| marilena.config.mjs
│ package.json
│ input
│ └──common-en.json // common json variables for all en emails
│ └──common-it.yaml // common yaml variables for all it emails
│ └──buy // email name
││││││└─── index.html
││││││└─── en
│││││││││││└── variables.json // json variables for en buy email
││││││└─── it
│││││││││││└── variables.yaml // yaml variables for it buy email

3 - fill your emails template with MJML syntax

<mjml>
  <mj-body>
    <mj-section>
      <mj-column>
        <!-- eta js example, read below about template engine -->
        <mj-text>hello <%= it.user %></mj-text>
      </mj-column>
    </mj-section>
  </mj-body>
</mjml>

4 - run one of these 2 commands

# open a server on http://localhost:8080
npm run start

# build all emails based on config
npm run build

Configuration

Under the hood a default configuration will be loaded but a file marilena.config.mjs allow us to set: | name | required | description | default | | ------------------ | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------- | | inputFolder | | folder where email are in the project. Path is relative to marilena.config.mjs | ./input | | outputFolder | | folder used for generated email (when run build command). Path is relative to marilena.config.mjs | ./output | | locales | | array of languages used. If you need only spanish email use an array of single value | ["en"] | | templateOptions | | if you chose to use one of supported engines, this part is mandatory to setup custom partial and other settings for the template engine selected. Read below for some use cases | empty | | mjmlParsingOptions | | options passed to mjml render. See: mjml options | | htmlVersion | | function of type (emailName: string, locale: string) => string. If set, this function allow to customize the output html filename. The function must return file name es: ${emailName}-${locale}.html | index.html | | textVersion | | function of type (emailName: string, locale: string) => string. If set, this function allow to generate text version of email stripping all html. The function must return file name es: ${emailName}-${locale}-text-version.txt | | sendTestOptions | | option in case you want to send the email to some account for testing. Setting this should add send-email button during development: Read below for some use cases | | fillFakeMetaData | | function of type (outputHtml: string, fakeData: object) => string. If set, this function allow to "simulate" a backend, parsing final output and replace with fake data. See dedicate section for details. |

Load env variables

Marilena uses dotenv out of the box. So if you create .env file (or it is created by runnning create-example) marilena will load variables from there.

About templateOptions

This project can producte output html from input template. But in a real word probably we store variables in some part and render some content multiple times (example a footer). In this case templateOptions can define:

• engine: eta or handlebars are supported. These deps are peer-dependency so if you want to use ones please install that as dependency.
• prepareEngine: define a callback where we can setup our engine. Basically you can define all things before the render. For example:

templateOptions: {
  engine:  "eta",
  prepareEngine: (eta) => {
    // eta is an istance of new Eta() so you need to set at least views options for templates/layout/partials
    eta.configure({
      views: path.join(process.cwd(), "input"),
    });
    // we can call all eta-js api like:
    eta.loadTemplate(...);
  },
},

templateOptions: {
  engine:  "handlebars",
  prepareEngine: (h) => {
    // we can register partial like:
    // handlebars is same of var h = require("handlebars");
    h.registerPartial("myPartial", "partial with {{ user }}");
  },
},

About sendTestOptions

This option provides a fast way to test email sending an email to real account. You shoud pass also createTransport function that return a Transporter. See nodemailer tutorial

Example marilena.config.mjs to work with Aws SES:

import * as aws from "@aws-sdk/client-ses";
import nodemailer from "nodemailer";

export default {
  ...config,
  sendTestOptions: {
    to: "[email protected]",
    from: "[email protected]", // this is not random email, but should be registered in you provider
    createTransport: () =>
      nodemailer.createTransport({
        SES: {
          ses: new aws.SES({
            apiVersion: "2010-12-01",
            region: "us-east-1",
            credentials: {
              accessKeyId: process.env.AWS_ACCESS_KEY || "secret",
              secretAccessKey: process.env.AWS_SECRET || "secret",
            },
          }),
          aws,
        },
      }),
  },
};

Example marilena.config.mjs to work with forwardemail or other custom setting;

import nodemailer from "nodemailer";

export default {
  ...config,
  sendTestOptions: {
    to: "[email protected]",
    from: "[email protected]", // this is not random email, but should be registered in you provider
    createTransport: () =>
      nodemailer.createTransport({
        host: "smtp.forwardemail.net",
        port: 465,
        secure: true,
        auth: {
          // TODO: replace `user` and `pass` values from <https://forwardemail.net>
          user: "[email protected]",
          pass: "REPLACE-WITH-YOUR-GENERATED-PASSWORD",
        },
      }),
  },
};

About fillFakeMetaData

In the real world the html produced by marilena is consumed by a backend. Probably this backend will fill email with real data using some template engine like jinja (php) or handlebars (php js) or blocks (go) etc. In some case we can mock a minimal behavior. This is useful for:

• render email with custm data
• test a send with some data

Follow these step:

• add fillFakeMetaData in marilena.config.mjs

import Handlebars from "handlebars";

export default {
  /* this example is made with Handlebars but you can use any js template engine */
  fillFakeMetaData: (outputHtml, fakeData) => {
    const template = Handlebars.compile(outputHtml);
    return template(fakeData);
  },
};

• create metadata.json or metadata.yml under [inputFolder]/[emailName]/[locale] path (same path of variables).

{
  "user": "Diego Tonini",
  "people": [
    {
      "name": "Luca Pavesi",
      "age": 23
    }
  ]
}

Add css/scss style

You have some options to apply styles on your email:

• Use <mj-style> tag (read MJML documentatation)

<mj-style inline="inline">
  .blue-text div {
    color: blue !important;
  }
</mj-style>

• create a style.css inside inputFolder and import in mj-include tag. Path start from root directory of the project (like package.json):

<mjml>
  <mj-include path="input/styles.css" type="css" css-inline="inline"/>
  <mj-body>
    <!-- other mjml nodes -->
  </mj-body>
</mjml>

• create a style.scss inside inputFolder. A compiled css will be added to the <head> of document.

🚀 Features

• [x] MJML support
• [x] load variables with template engine
• [x] multi language out of the box
• [x] eta.js, handlebars (need to install if you use one of these engines)
• [x] fast-refresh on variables changes
• [x] fast-refresh on template change
• [x] fast-refresh on css change
• [x] load varibles from yaml/json format
• [x] load common variables
• [x] pass option to MJML render
• [x] send test email (nodemailer, aws ses)

🏗️ Roadmap (PRs are welcome 😀)

• [ ] liquid, ejs, nunjucks, mustache, dot
• [ ] config in typescript
• [ ] fast-refresh on config change
• [ ] snaphost test for each email out of the box