Mail Mime Builder

RFC-2822, RFC-2045 and RFC-2049 compliant raw email message generator.

This is a fork of mimetext with some improvements like: zero dependency, improved validation.

Installation

npm install mail-mime-builder

Usage

// cjs
const {createMimeMessage} = require('mail-mime-builder')
// es
import {createMimeMessage} from 'mail-mime-builder'

// create a simple plain text email
const msg = createMimeMessage()
msg.setSender({name: 'Lorem Ipsum', addr: '[e-mail]'})
msg.setRecipient('[e-mail]')
msg.setSubject('🚀 Issue 49!')
msg.addMessage({
    contentType: 'text/plain',
    data: `Hi,
I'm a simple text.`
})
const raw = msg.asRaw()
/*
Date: Sun, 24 Oct 2021 04:50:32 +0000
From: "Lorem Ipsum" <[e-mail]>
To: <[e-mail]>
Message-ID: <[e-mail]>
Subject: =?utf-8?B?8J+agCBJc3N1ZSA0OSE=?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8

Hi,
I'm a simple text.
*/

Different Ways Of Adding Recipients

There are more than one method and format to add recipients:

// adds recipient to To field by default
msg.setRecipient('Firstname Lastname <[e-mail]>')
// you can specify To, Cc, Bcc
msg.setRecipient('Firstname Lastname <[e-mail]>', {type: 'Cc'})
// as object, only addr is required
msg.setRecipient({addr: '[e-mail]', name: 'Firstname Lastname', type: 'Bcc'})
// shortcut methods
msg.setTo('[e-mail]')
msg.setCc('[e-mail]')
msg.setBcc('[e-mail]')
// multiple recipient at once
msg.setRecipients('[e-mail]', 'Firstname Lastname <[e-mail]>', {addr: '[e-mail]'})

// similarly you can set the sender
msg.setSender('First Last <[e-mail]>')
msg.setSender({name: 'First Last', addr: '[e-mail]'})

HTML Message With Plain Text Fallback And Attachments

You can set html and plain text messages both and recipients mail client will render however they think appropriate.

The example below demonstrates more sophisticated email content including inline attachments and regular attachments.

const msg = createMimeMessage()
msg.setSender('[e-mail]')
msg.setRecipients('[e-mail]')
msg.setSubject('Testing mail-mime-builder 🐬 (Plain Text + HTML With Mixed Attachments)')
msg.addMessage({
    contentType: 'text/plain',
    data: 'Hello there,' + EOL + EOL +
        'This is a test email sent by MimeText test suite.'
})
// specify inline attachment's content id inside img src tag. <img src="cid:[ID]">
msg.addMessage({
    contentType: 'text/html',
    data: 'Hello there,<br><br>' +
        'This is a test email sent by <b>MimeText</b> test suite.<br><br>' +
        'The term MimeText above supposed to be bold. Are you able to see it?<br><br>' +
        'Below, there should be a small image that contains little black dots:<br><br>' +
        '<img src="cid:dots123456"><br><br>' +
        'Best regards.'
})
msg.addAttachment({
    filename: 'sample.jpg',
    contentType: 'image/jpg',
    data: '...base64 encoded data...'
})
msg.addAttachment({
    filename: 'sample.txt',
    contentType: 'text/plain',
    data: '...base64 encoded data...'
})
// this is inline attachment!
msg.addAttachment({
    inline: true,
    filename: 'dots.jpg',
    contentType: 'image/jpg',
    data: '...base64 encoded data...',
    headers: {'Content-ID': 'dots123456'}
})
const raw = msg.asRaw()
/*
Date: Sun, 26 Mar 2023 13:27:15 +0000
From: <[e-mail]>
To: <[e-mail]>
Message-ID: <[e-mail]>
Subject: =?utf-8?B?VGVzdGluZyBNaW1lVGV4dCDwn5CsIChQbGFpbiBUZXh0ICsgSFRNTCBXaXRoIE1peGVkIEF0dGFjaG1lbnRzKQ==?=
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=giev1zqo579

--giev1zqo579
Content-Type: multipart/related; boundary=hl6rtnn5jq

--hl6rtnn5jq
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 7bit

Hello there,<br><br>This is a test email sent by <b>MimeText</b> test suite.<br><br>The term MimeText above supposed to be bold. Are you able to see it?<br><br>Below, there should be a small image that contains little black dots:<br><br><img src="cid:dots123456"><br><br>Best regards.

--hl6rtnn5jq
Content-ID: <dots123456>
Content-Type: image/jpg; name="dots.jpg"
Content-Transfer-Encoding: base64
Content-Disposition: inline; filename="dots.jpg"

/9j/4AAQSkZJRgABAgEASABIAAD/2wCEAAEBAQEBAQEBAQEBAQEBAQ...........BPwAp/9k=
--hl6rtnn5jq--
--giev1zqo579
Content-Type: image/jpg; name="sample.jpg"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="sample.jpg"

/9j/4AAQSkZJRgABAg...........befPb4N8Hn4A/9k=

--giev1zqo579
Content-Type: text/plain; name="sample.txt"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="sample.txt"

SGVsbG8gdGhlcmUu
--giev1zqo579--
*/

Encoding The Output

If you ever need to get base64-websafe encoded version of the raw data, you can use asEncoded() method.

// it first gets the raw version and then encodes it.
msg.asEncoded()

Use Cases

mail-mime-builder is useful for email sending platforms and end-user apps whose email clients require raw email messages.

Cloudflare Mail

import { EmailMessage } from "cloudflare:email";
import { createMimeMessage } from "mail-mime-builder";

export default {
 async fetch(request, env) {
   const msg = createMimeMessage();
   msg.setSender({ name: "GPT-4", addr: "<SENDER>@example.com" });
   msg.setRecipient("<RECIPIENT>@example.com");
   msg.setSubject("An email generated in a worker");
   msg.addMessage({
       contentType: 'text/plain',
       data: `Congratulations, you just sent an email from a worker.`
   });

   var message = new EmailMessage(
     "<SENDER>@example.com",
     "<RECIPIENT>@example.com",
     msg.asRaw()
   );
   try {
     await env.SEB.send(message);
   } catch (e) {
     return new Response(e.message);
   }

   return new Response("Hello Send Email World!");
 },
};