mail-compose

A simple library that composes MIME-encoded emails from human-friendly contents (like text, files, images), which can be fed into MTA/MSAs like sendmail, msmtp, ssmtp.

Basic Usage

Install the package:

npm install mail-compose

Create a mail object:

const Mail = require("mail-compose");
const fs = require("fs");

let mail = new Mail({
    from: {
        name: "Alice",
        address: "alice@example.com"
    },
    to: {
        name: "Bob",
        address: "bob@example.com"
    },
    subject: "Photo",
    message: "My new haircut!",
    attachments: [
        {
            filename: "new_look.jpg",
            content: fs.readFileSync("/home/alice/Desktop/new_look.jpg")
        }
    ]
});

Once the mail is created, you can call getMail() to get the composed mail, or getMailHeader(), getMailBody() if you want them to come separately.

console.log(mail.getMail());

Output:

From: "Alice" <alice@example.com>
To: "Bob" <bob@example.com>
Subject: Photo
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="boundary-f81912011413b3a9b1a2fbbd1bd2600b"

--boundary-f81912011413b3a9b1a2fbbd1bd2600b
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: base64

TXkgbmV3IGhhaXJjdXQh
--boundary-f81912011413b3a9b1a2fbbd1bd2600b
Content-Type: image/jpeg
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="new_look.jpg"

/9j/4AAQSkZJRgABAQAASABIAAD/4QDORXhpZgAATU0AKgAAAAgABgESAAMAAAABAAEAAAEaAAU
AAAABAAAAVgEbAAUAAAABAAAAXg (... remaining base64-encoded data ...)
--boundary-f81912011413b3a9b1a2fbbd1bd2600b--

Parameters

The Mail class requires an object parameter:

{
    from: string|{name: string, address: string},
    to: string|{name: string, address: string},
    subject: string,
    message: string|{plainText: string, htmlText: string, assets: [string|{filename: string, content: Buffer}]}
    attachments: [string|{filename: string, content: Buffer}]
}

While UTF-8 is the de facto standard of modern days coding, this library accepts and only accepts UTF-8 parameters, whether it's the mail's subject or the name of sender/recipient.

from, to

These 2 parameters require either a string of mail address, or an object that includes a name, and an address.

let mail = new Mail({
    from: {
        name: "Alice", 
        address: "alice@example.com"
    },
    to: "bob@example.com",
    /* ... */
});

The address format defined by RFC 2822 should also work. However, you may want to stick with the name+address combination since the library will encode the name for you if any non-ASCII character presents.

let mail = new Mail({
    from: "Alice <alice@example.com>",
    to: "Bob <bob@example.com>",
    /* ... */
});

message

To get started quickly, drop a string here, as it will be parsed as text/plain content.

let mail = new Mail({
    /* ... */
    message: "Hello!",
    /* ... */
});

To send HTML contents, use:

let mail = new Mail({
    /* ... */
    message: {
        htmlText: "<p>Hello!</p>",
        plainText: "Hello!"
    },
    /* ... */
});

While using htmlText alone is possible, it's recommended to provide both plain texts along with HTML text, as it will be composed into a multipart/alternative, thus improving compatibilities/readabilities on some clients.

It's also possible to embed image assets into the mail's body.

let mail = new Mail({
    /* ... */
    message: {
        htmlText: "<p>My new haircut!</p><img src=\"new_look.jpg\">",
        plainText: "My new haircut!",
        assets: [
            {
                filename: "new_look.jpg",
                content: fs.readFileSync("/home/alice/Desktop/new_look.jpg")
            }
        ]
    },
    /* ... */
});

The message.assets array receives a list of file that shares the same format with attachments, which we'll cover later.

attachments

To compose mails with attachments, use:

let mail = new Mail({
    /* ... */
    attachments: [
        {
            filename: "transcations_q1.xlsx",
            content: fs.readFileSync("/path/transcations_q1.xlsx")
        },
        {
            filename: "transcations_q2.xlsx",
            content: fs.readFileSync("/path/transcations_q2.xlsx")
        }
    ]
});

To attach existing files more simply, you can also put their path directly into the array.

let mail = new Mail({
    /* ... */
    attachments: [
        "/path/transcations_q1.xlsx",
        "/path/transcations_q2.xlsx"
    ]
});

The name of these files will keep as is, however.