How to send email from localhost in PHP?

📧 PHPMailer is a code library to send emails safely and easily via PHP code from a web server, and you can also send emails from localhost.

Here you will learn how to send emails using PHPMailer with Gmail SMTP and for authentication, we will use the XOAUTH2 mechanism.

Sending emails using PHPMailer

1. Create a folder inside the localhost directory, and name it whatever you want, I called it 📁 phpmailer.

2. Install the phpmailer and oauth2-google via composer inside the phpmailer directory.

 composer require phpmailer/phpmailer league/oauth2-google

3. Move the get_oauth_token.php to the root of the phpmailer folder.

#from this
phpmailer/vendor/phpmailer/phpmailer/get_oauth_token.php

#to this
phpmailer/get_oauth_token.php

How to get Google Client ID and Secret for PHPMailer?

---

4. After getting the Client-ID, Client-Secret, and refresh token, here is the PHP code to send emails –

<?php
// Add your Client ID, Secret and Refresh token
$clientID = "654563609574-7f5a4c2ev************99m0i1.apps.googleusercontent.com";
$clientSecret = "GOCSPX-opn_K************NLMPB";
$refreshToken = "1//0g8Dng2fJk3AuC********NwF-L9IrQVKMzy6t***********sVCDSDEYCW2j8z*****nTYiXO3VzuthW-cico";
$email = '[email protected]';

// Import PHPMailer classes into the global namespace
// These must be at the top of your script, not inside a function
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;
use PHPMailer\PHPMailer\OAuth;
use League\OAuth2\Client\Provider\Google;

// Load Composer's autoloader
require 'vendor/autoload.php';

// Create an instance; passing `true` enables exceptions
$mail = new PHPMailer(true);

try{
  $mail->isSMTP(); // Tell PHPMailer to use SMTP

// Enable SMTP debugging
/**
 * SMTP::DEBUG_OFF -> off (for production use)
 * SMTP::DEBUG_CLIENT -> client messages
 * SMTP::DEBUG_SERVER -> client and server messages
 */
  $mail->SMTPDebug = SMTP::DEBUG_SERVER;

  // Set the hostname of the mail server
  $mail->Host = 'smtp.gmail.com';
  
  // Set the SMTP port number - 587 for authenticated TLS, a.k.a. RFC4409 SMTP submission
  $mail->Port = 587;

  // Set the encryption mechanism to use - STARTTLS or SMTPS
  $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;

  // Whether to use SMTP authentication
  $mail->SMTPAuth = true; 
  
  // Set AuthType to use XOAUTH2
  $mail->AuthType = 'XOAUTH2';

  // Create a new OAuth2 provider instance
  $provider = new Google(
    [
        "clientId" => $clientID,
        "clientSecret" => $clientSecret,
    ]
  );

  // Pass the OAuth provider instance to PHPMailer
  $mail->setOAuth(
    new OAuth(
        [
            "provider" => $provider,
            "clientId" => $clientID,
            "clientSecret" => $clientSecret,
            "refreshToken" => $refreshToken,
            "userName" => $email,
        ]
    )
  );

  /*
  * Set who the message is to be sent from
  * For gmail, this generally needs to be the same as the user you logged in as
  */
  $mail->setFrom($email, 'Name of the sender');

  // Set who the message is to be sent to
  $mail->addAddress('[email protected]');
  /* if you want to send email to multiple users, then add the email addresses you which you want to send. e.g -
  * $mail->addAddress('[email protected]');
  * $mail->addAddress('[email protected]');
  */

  $mail->isHTML(true); # Set email format to HTML
  $mail->Subject = "Subject Of the email";
  $mail->Body    = 'This is the HTML message body <b>in bold!</b>';
  $mail->AltBody = 'This is the body in plain text for non-HTML mail clients';

  /*
  * For Attachments -
  * $mail->addAttachment('/var/tmp/file.tar.gz'); Add attachments
  * $mail->addAttachment('/tmp/image.jpg', 'new.jpg'); You can specify the file name in the second parameter
  */

  // Call the send() method to send the mail.
  $mail->send();
  echo 'Message has been sent';
}
catch(Exception $e){
  echo "Message could not be sent. Mailer Error: {$mail->ErrorInfo}";
}

---

Send emails using PHPMailer with HTML Form

Now we will see how to send emails using PHPMailer with HTML Form. Here is the Demo –

In the same project folder (phpmailer) we have to make three files – send.php, index.php, and style.css

send.php file contains the send_mail() function used to send emails, this function has one parameter ($form_data) and takes form data as an array.

<?php
// Import PHPMailer classes into the global namespace
// These must be at the top of your script, not inside a function
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\Exception;
use PHPMailer\PHPMailer\OAuth;
use League\OAuth2\Client\Provider\Google;

require_once __DIR__ . "/vendor/autoload.php";

function send_mail($form_data)
{
  // Put your client id, secret, refresh token, and email
  $clientID = "654563609574-7f5a*****oj0bt**0i1.apps.googleusercontent.com";
  $clientSecret = "GOCSPX-opn_K*********KNLMPB";
  $refreshToken = "1//0g8Dng2fJk3AuCgY*****GBASNwF-L9IrQV********LbUp6lDVatPsVCD*****TYiXO3VzuthW-cico";
  $sender_email = "[email protected]";

  $provider = new Google(
    [
        "clientId" => $clientID,
        "clientSecret" => $clientSecret,
    ]
  );

  $oAuth = new OAuth(
    [
        'provider' => $provider,
        'clientId' => $clientID,
        'clientSecret' => $clientSecret,
        'refreshToken' => $refreshToken,
        'userName' => $sender_email,
    ]
  );

  $mail = new PHPMailer(true);
  try {
    $mail->isSMTP();
    $mail->SMTPDebug = SMTP::DEBUG_OFF;
    $mail->Host = 'smtp.gmail.com';
    $mail->Port = 587;
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->SMTPAuth = true;
    $mail->AuthType = 'XOAUTH2';
    $mail->setOAuth($oAuth);
    $mail->setFrom($sender_email, "Sender Name");
    $mail->addAddress($form_data["email"]);
    $mail->isHTML(true);
    $mail->Subject = $form_data["subject"];
    $mail->Body = $form_data["message"];

    // If there is any attachment to send
    if ($form_data["atch"]) {
      $mail->addAttachment($form_data["atch"]["tmp_name"], $form_data["atch"]["name"]);
    }
    $mail->send();
    return true;
  } catch (Exception $e) {
    return false;
  }
}

index.php contains the HTML form and here we will call the send_mail() function to send email, Other than it contains some validations –

<?php
require_once __DIR__ . "/send.php";
// This variables are for showing messages
$error = false;
$success = false;

if (
  isset($_POST["email"]) &&
  isset($_POST["subject"]) &&
  isset($_POST["message"]) &&
  isset($_FILES["attachment"])
) {  
  
  $email = trim($_POST["email"]);
  $subject = trim($_POST["subject"]);
  $message = trim($_POST["message"]);
  $file = $_FILES["attachment"];

  // Email Validation
  if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    $error = "Invalid Email address";
  }
  // If there is no attachment to send then set the $file = false;
  if ($file["error"] === 4) {
    $file = false;
  }
 
  // Chekcing File size max 25MB
  if ($file && ($file["error"] === 1 || $file["size"] > 1048576 * 25)) {
    $error = "File is too large Max 25MB";
  }

  // If there is no error then cll the sen_mail() function
  if ($error === false) {

    $form_data = [
      "email" => $email,
      "subject" => $subject,
      "message" => $message,
      "atch" => $file
    ];

    $result = send_mail($form_data);

    if ($result) {
      $success = "Email has been sent.";
    } else {
      $error = "Email could not be delivered";
    }
  }
}
?>
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>PHPMailer Send Emails</title>
  <link href="./style.css" rel="stylesheet">
</head>

<body>

  <div class="container">
    <h1>PHPMailer Send Emails</h1>
    <form action="" method="POST" enctype="multipart/form-data">
      <label for="email">To:</label>
      <input type="email" name="email" id="email" autocomplete="off" placeholder="Email address" />
      <label for="subject">Subject:</label>
      <input type="text" name="subject" id="subject" autocomplete="off" placeholder="Subject">
      <label for="message">Message:</label>
      <textarea name="message" id="message" placeholder="Message"></textarea>
      <label for="attachment">Attachment: (Max 25MB)</label>
      <input type="file" name="attachment" id="attachment">
      <?php echo ($success) ? '<div class="message">' . $success . '</div>' : ''; ?>
      <?php echo ($error) ? '<div class="message error">' . $error . '</div>' : ''; ?>
      <button type="submit">Send</button>
    </form>
  </div>
  <script>
    // this js code stops the multiple form submission on page refresh
    if (window.history.replaceState) {
      window.history.replaceState(null, null, window.location.href);
    }
  </script>
</body>
</html>

style.css contains the stylesheet for the HTML Form –

@import url('https://fonts.googleapis.com/css2?family=Open+Sans:[email protected];700&display=swap');
*{
  box-sizing: border-box;
}
:root{
  --main-color:#7A3653;

}
html{
  font-size: 16px;
}
body{
  font-family: 'Open Sans', sans-serif;
  background:#f7f7f7;
}
h1{
  text-align: center;
  margin-bottom: 0;
}
form{
  display: flex;
  flex-direction: column;
  max-width: 500px;
  margin: 0 auto;
  padding: 20px;
}

button,input,textarea{
  font-family: 'Open Sans', sans-serif;
  font-size: 1rem;
  padding: 10px;
}

button[type="submit"],
input,textarea{
  border: 1px solid rgba(0, 0, 0, .3);
  border-radius: 3px;
  outline: none;
}
textarea{
  resize: vertical;
  min-height: 120px;
}

input:is(:hover,:focus),
textarea:is(:hover,:focus){
  border-color: var(--main-color);
}

button[type="submit"]{
  background: var(--main-color);
  color: white;
  cursor: pointer;
  font-weight: 700;
  margin-top: 15px;
}

button[type="submit"]:hover{
  outline:var(--main-color) solid 2px;
  outline-offset: 2px;
}

label{
  font-weight: 700;
  margin: 10px 0 3px 0;
}

.message{
  border: 2px solid #4BB543;
  border-radius: 3px;
  background: hsl(116, 46%, 90%);
  margin-top: 15px;
  padding: 10px;
}
.error{
  border-color: #ff3333;
  background: hsl(0, 100%, 90%);
}