SendGrid email forwarding hook on free plan

Cost-effective solutions are essential in software development. SendGrid’s free plan covers sending emails, but receiving emails requires a paid plan. This article demonstrates how to use the SendGrid Inbound Parse webhook to forward incoming emails to your own email account at no additional cost.

Create /api/sendgrid/mail-forwarding endpoint

Choose your best node.js framework (e.g.: express, next.js, nuxt.js, nest.js, …) and create a new endpoint with the name you want.

First, install the required packages (@sendgrid/mail and multer):

npm i @sendgrid/mail multer --save

Here is the TS code snippet, that I use to forward incoming emails to my personal email account.

// /sendgrid/mail-forwarding.ts
import sendGridMail from '@sendgrid/mail';
import multer from 'multer';

const SENDGRID_API_KEY = 'API_KEY'; // Use your own SendGrid api_key
const SENDGRID_TO_EMAIL = 'to@example.com'; // Use your personal email address to receive mails
const SENDGRID_FROM_EMAIL = 'from@example.com'; // Use the email address or domain you verified on SendGrid

const initMiddleware = (middleware: any) => {
	return (req: Request, res: Response) =>
		new Promise((resolve, reject) => {
			middleware(req, res, (result: any) => {
				if (result instanceof Error) {
					return reject(result);
				}
				return resolve(result);
			});
		});
};

sendGridMail.setApiKey(SENDGRID_API_KEY!);

type ResponseData = {};

const upload = multer();
const multerAny = initMiddleware(
	upload.any() // Note that Multer limits to 1MB file size by default
);

export default async (req: Request, res: Response<ResponseData>) => {
	if (req.method !== 'POST') {
		return res.status(405).json({});
	}

	await multerAny(req, res);

	const body = req.body;
	if (!body['text'] && !body['html']) {
		return res.status(400).json({});
	}

	const mailData: sendGridMail.MailDataRequired = {
		to: SENDGRID_TO_EMAIL,
		from: SENDGRID_FROM_EMAIL!,
		replyTo: body['from'],
		subject: body['subject'] ?? 'Forwarded email',
		text: body['text'],
		html: body['html']
	};

	try {
		await sendGridMail.send(mailData);
	} catch (_error: any) {
		return res.status(500).json({});
	}

	res.status(200).json({});
};

SendGrid - Inbound Parse

Visit SendGrid / Settings page, here is the link. On the screen press the Add Host & URL and set the following options:

• Receiving Domain: // Choose your domain
• Destination URL: // Location of your deployed API endpoint
• Additional Options
  • SPAM CHECK ✅
  • SEND RAW ❌

Conclusion

This lightweight forwarding endpoint has been reliably processing hundreds of emails in production without issues.