converter.js

const fs = require('fs');
const emlformat = require('eml-format');
const htmlToImage = require('html-to-image');
const nodeHtmlToImage = require('node-html-to-image');

const input = 'sample.eml';
const output = 'image.png';

const eml = fs.readFileSync(input, 'utf-8');
emlformat.read(eml, function (error, data) {
  if (error) return console.log(error);

  nodeHtmlToImage({
    output,
    html: data.html
  }).then(() => console.log('The image was created successfully!'));
});