Sendgrid in Vercel not sending email in production - node.js

Question

I'm using SendGrid to send emails in my serverless Next.js project, deployed in Vercel, which works perfectly in development mode. But I'm having problems in production.
The error returned is:
contact-us-4c7332c1e7bfe2127d39.js:1 POST https://mywebsite.vercel.app/api/send 400
Yes, I enabled "Allow Less Secured Apps" in Google account and verify a Sender Identity in SendGrid.
Anybody experienced this kind of problem? How can I fix this?
This is the contact-us.js page
import Head from 'next/head'
import React, { useState } from 'react'
export default () => {
const [status, setStatus] = useState({
submitted: false,
submitting: false,
info: { error: false, msg: null }
})
const [inputs, setInputs] = useState({
name: '',
phone: '',
email: '',
message: ''
})
function SubmitButton(){
if (inputs.name && inputs.email && inputs.message) {
return <button type="submit" className="btn-submit" disabled={status.submitting}> {!status.submitting ? !status.submitted ? 'Submit' : 'Submitted' : 'Submitting...'} </button>
} else {
return <button type="submit" className="btn-submit" disabled>Submit</button>
};
};
const handleResponse = (status, msg) => {
if (status === 200) {
setStatus({
submitted: true,
submitting: false,
info: { error: false, msg: msg }
})
setInputs({
name: '',
phone: '',
email: '',
message: ''
})
} else {
setStatus({
info: { error: true, msg: msg }
})
}
}
const handleOnChange = e => {
e.persist()
setInputs(prev => ({
...prev,
[e.target.id]: e.target.value
}))
setStatus({
submitted: false,
submitting: false,
info: { error: false, msg: null }
})
}
const handleOnSubmit = async e => {
e.preventDefault()
setStatus(prevStatus => ({ ...prevStatus, submitting: true }))
const res = await fetch('/api/send', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify(inputs)
})
const text = await res.text()
handleResponse(res.status, text)
}
return (
<div className="contact">
<main>
<div>
<h2>Get in touch!</h2>
<h3>How can we help you?</h3>
</div>
<form onSubmit={handleOnSubmit}>
<div className="form-group">
<input
id="name"
type="text"
name="name"
onChange={handleOnChange}
required
value={inputs.name}
className={inputs.name ? "form-control active" : "form-control"}
/>
<label className="form-label" htmlFor="name">Name</label>
</div>
<div className="form-group">
<input
id="email"
type="text"
name="email"
onChange={handleOnChange}
required
value={inputs.email}
className={inputs.email ? "form-control active" : "form-control"}
/>
<label className="form-label" htmlFor="email">Email</label>
</div>
<div className="form-group">
<input
id="phone"
type="tel"
name="phone"
onChange={handleOnChange}
required
value={inputs.phone}
className={inputs.phone ? "form-control active" : "form-control"}
/>
<label className="form-label" htmlFor="phone">Phone</label>
</div>
<div className="form-group">
<textarea
id="message"
onChange={handleOnChange}
required
value={inputs.message}
className={inputs.message ? "form-control active" : "form-control"}
/>
<label className="form-label" htmlFor="message">Message</label>
</div>
<SubmitButton />
{status.info.error && (
<div className="message-feedback error">
<p>Error: {status.info.msg}</p>
</div>
)}
{!status.info.error && status.info.msg && (
<div className="message-feedback success">
<p>Thanks for messaging us!</p>
<p>We'll get back to you soon.</p>
</div>
)}
</form>
</main>
</div>
)
}
And the /api/send.js
const sgMail = require('#sendgrid/mail')
export default async function(req, res) {
sgMail.setApiKey(process.env.SENDGRID_API_KEY)
const { phone, email, message } = req.body
const msg = {
to: 'myemail#outlook.com', // Change to your recipient
from: 'mysenderemail#gmail.com', // Change to your verified sender
subject: `New Message From - ${email}`,
text: message,
html: `
<p>Phone: ${phone}</p>
<p>Sent from: ${email}</p>
<div>${message}</div>
`
}
try {
await sgMail.send(msg)
res.status(200).send('Message sent successfully.')
} catch (error) {
console.log('ERROR', error)
res.status(400).send('Message not sent.')
}
}
Thank you.