getNewMail.js

const fs = require('fs');
const path = require('path');
const { promisify } = require('util');
const writeFileAsync = promisify(fs.writeFile);
const s3etm = require('s3-emails-to-mongo');

// MAKE THIS PART DYNAMIC LATER
s3etm.configure({
    Bucket: 'zhillb-mail',
});

module.exports = async (req, res, next) => {
    try {
        const newMail = await s3etm();
        // check if new mail has attachment(s), if so save them
        await Promise.all(newMail.map((msg) => {
            if (msg.attachments.length) {
                return Promise.all(msg.attachments.map((attachment) => {
                    const file = attachment.content;
                    const cid = attachment.cid;
                    const filePath = path.join(__dirname, '..', 'data/uploads', cid);
                    return writeFileAsync(filePath, file).then(() => {
                        console.log('saved file: ' + filePath);
                        console.log('mime type: ', attachment.contentType);
                    }).catch((err) => {
                        console.log('err with file: ', err);
                        throw err;
                    })
                }));
            }
        }))
        res.json(newMail);
    } catch(err) {
        next(err);
    }
};