Nodemailer plugin for converting external images to email attachments

This plugin will convert external images in your nodemailer email to be inline ("CID-referenced") attachments within the email. Inline attachments are useful because they embed the image inside the actual email, so it's viewable even if the user is checking their email without an internet connection.

Local files will not be accessible with html alone. This Nodemailer plugin will take images in your email html in the form:

<img src="path/to/file.jpg">

and replace it with a CID-referenced attachment that works in all email clients.

Install

yarn add nodemailer-plugin-file2inline

or

npm install nodemailer-plugin-file2inline --save

Usage

1. Load the nodemailer-plugin-file2inline plugin:

var file2InlinePlugin = require('nodemailer-plugin-file2inline');

2. Attach it as a 'compile' handler for a nodemailer transport object

//Without options
nodemailerTransport.use('compile', file2InlinePlugin())

//With options
nodemailerTransport.use('compile', file2InlinePlugin({
	cidPrefix: "prefix_",
	htmlFilePath: "path/relative/to/the/html/file",
	maxWidth: 600
))

Options are:

• cidPrefix: allows to set CID prefix¹ {cidPrefix: 'somePrefix_'}, then all inline images will have prefix in cid, i.e.: cid:somePrefix_5fe3b631c651bdb1.
• htmlFilePath: path to the folder where the html file is, relative to the current working folder
• maxWidth: if this options is set, all images will have the "width" attribute set to the value

Example

var nodemailer = require('nodemailer');
var file2InlinePlugin = require('nodemailer-plugin-file2inline');

let transporter = nodemailer.createTransport({
    sendmail: true,
    newline: 'unix',
});
transporter.use('compile', file2InlinePlugin({cidPrefix: 'somePrefix_'}));
transporter.sendMail({
    from: 'me@example.com',
    to: 'hello@mixmax.com',
    html: '<img src="external/image.png">'
});

Changelog

• 1.0.0 Initial release

References

¹ It might be useful for reply email processing, example with MailParser

mp.on("attachment", function(attachment, mail){
    if (!attachment.contentId.includes('somePrefix')) { // process only images attached by user in reply
        // ...
    }
});

License

MIT