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  • Prerqusitories
  • Contact form
  • Gatsby function (API)

How to send email with Gatsby functions and Sendgrid

January 2022

2 min

I believe that every personal blog and portfolo website should have a way to reach out to the owner of the website. It is utterly important to have a contact form if you are a freelancer and want to reach out to new clients or a comment section if you are writing a blog where you would like to get feedback or start a discussion between you and the reader.

In this article will I go through how you can create a contact form with Gatsby and how to actually send an email via Gatsby funtions with a sendgrid implementation.


It is required to have a basic understanding of ReactJS and GatsbyJs alongside a little knowlegde about NodeJS works.
Furthere more should you have created an Sendgrid account and verified you email as a single sender.

Contact form

For the sake of the simplicity do I use react-hook-form instead of managing the form statte myself. In the ideal world would you want to use yup as a resolver to validate the input but I am not going through this in this article.

import React from "react";
import { useForm } from "react-hook-form";

export const ContactForm = () => {
  const { register, handleSubmit } = useForm();

  const onSubmit = (data) => {
    throw new Error("Method not implemented.");

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <label for="name">Name</label>
      <input type="text" {...register("name")} />

      <label for="email">Email</label>
      <input type="email" {...register("email")} />
      <label for="subject">Subject</label>
      <input type="text" {...register("subject")} />
      <label for="message">Message</label>
      <textarea {...register("message")} />
      <input type="submit" value="Send email" />

This is a minimal snippet of how the form could look like, we have a basic form, managed by react-hook-form which contains 4 fields and a submit button which calls onSubmit() which is going to be defined in a brief moment.

Gatsby function (API)

I don't know if you have noticed that in some point of Gatsby v3 a new entry in the 404 page appered, namely the Functions entry. This is baically a way to combine an API with gatsby, hence the name serverless functions. The syntax for a Gatsby function is bassicaly standard express.

All we need to do is create an api folder under src/, create a file sendMail.js

const sendgrid = require("@sendgrid/mail");

const handler = (req, res) => {
  const { method, body } = req;

  let message;

  try {
    // check if the request contains a body
    if (body) { = process.env.SENDGRID_AUTHORIZED_EMAIL;
      message.from =
      message.subject = body.subject;
      message.text = body.text;
      message.html = body.text;

    return sendgrid.send(message).then(
      () => {
          message: "Email sent",
      (error) => {
        if (error.response) {
          return res.status(500).json({
            error: error.response,
  } catch (err) {
    return res.status(500).json({ message: "There was an error", error: err });

module.exports = handler;