Cómo enviar correo electrónico mediante la función mail() de PHP

¿Qué es el correo PHP?

PHP mail is the built-in PHP function that is used to send emails from PHP scripts.

La función de correo acepta los siguientes parámetros:

• Correo electrónico
• Asunto
• Mensaje
• CC or BCC email addresses

Why and When to use PHP mail

The mail function is useful in many situations:

• It is a cost effective way of notifying users of important events.
• Permita que los usuarios se comuniquen con usted por correo electrónico proporcionando un formulario de contacto en el sitio web que envía por correo electrónico el contenido proporcionado.
• Developers can use it to receive system errors by email.
• Puede usarlo para enviar correos electrónicos a los suscriptores de su boletín informativo.
• You can use it to send password reset links to users who forget their passwords.
• You can use it to email activation and confirmation links. This is useful when registering users and verifying their email addresses.

Envío de correo electrónico mediante PHP

The PHP mail function has the following basic syntax.

<?php
mail($to_email_address,$subject,$message,[$headers],[$parameters]);
?>

AQUÍ,

• “$to_email_address” es la dirección de correo electrónico del destinatario del correo
• “$subject” es el asunto del correo electrónico
• “$message” es el mensaje a enviar.
• “[$headers]” is optional; it can be used to include information such as CC and BCC.
  • CC is the acronym for carbon copy. It is used when you want to send a copy to an interested person, i.e. a complaint email sent to a company can also be sent as CC to the complaints board.
  • BCC is the acronym for blind carbon copy. It is similar to CC, but the email addresses included in the BCC section are not shown to the other recipients.

Fácil Mail Transmission Protocolo (SMTP)

PHP mail uses the Simple Mail Transmission Protocolo (SMTP) para enviar correo.

On a hosted server, the SMTP settings would already have been set.

The SMTP mail settings can be configured from the “php.ini” file in the PHP installation folder.

To configure SMTP settings on your localhost, assuming you are using XAMPP on Windows, locate the “php.ini” file in the directory “C:\xampp\php”.

• Open it using Notepad or any text editor. We will use Notepad in this example. Click on the Edit menu.

• Click on the Find… menu

• The Find dialog will appear

• Click on the Find Next button

Locate the entries under [mail function]. The default lines usually look like this:

• ; SMTP = servidor local
• ; puerto_smtp = 25

Remove the semicolons before SMTP and smtp_port, and set SMTP to your Servidor SMTP and the port to your SMTP port. Your settings should look as follows:

• SMTP = smtp.ejemplo.com
• puerto_smtp = 25

Note: the SMTP settings can be obtained from your web hosting provider. If the server requires authentication, then add the following lines:

• nombre_usuario_autenticación = nombre_usuario_ejemplo@ejemplo.com
• contraseña_autenticación = contraseña_ejemplo

Save the new changes and restart the APACHE servidor.

PHP Mail Ejemplo

Let us now look at an example that sends a simple mail.

<?php
$to_email = 'name@example.com';
$subject = 'Testing PHP Mail';
$message = 'This mail is sent using the PHP mail function';
$headers = 'From: noreply@example.com';
mail($to_email,$subject,$message,$headers);
?>

Salida:

Note: the above example only takes the 4 mandatory parameters. You should replace the above fictitious email address with a real email address.

Desinfección de entradas de correo electrónico de los usuarios

El ejemplo anterior utiliza valores codificados en el código fuente para la dirección de correo electrónico y otros detalles para simplificar.

Let us assume you have to create a contact us form where users fill in the details and then submit.

• Users can accidentally or intentionally inject code in the headers, which can result in sending spam mail.
• Para proteger su sistema de este tipo de ataques, puede crear una función personalizada que desinfecte y valide los valores antes de enviar el correo.

Let us create a custom function that validates and sanitizes the email address using the filter_var built-in function. The filter_var function is used to sanitize and validate user input data.

Tiene la siguiente sintaxis básica.

<?php
filter_var($field, SANITIZATION_TYPE);
?>

AQUÍ,

• “filter_var(…)” es la función de validación y desinfección
• “$campo” es el valor del campo a filtrar.
• “SANITIZATION_TYPE” is the type of sanitization to be performed on the field, such as:
  • FILTRO_VALIDAR_CORREO_ELECTRÓNICO – returns true for valid email addresses and false for invalid email addresses.
  • FILTRO_DESINFECTAR_CORREO_ELECTRÓNICO – removes illegal characters from email addresses, so an address with stray characters is reduced to info@domain.com.
  • FILTRO_DESINFECTAR_URL – removes illegal characters from URLs, leaving a clean address such as https://www.example.com.
  • FILTER_SANITIZE_STRING – removes tags from string values, so <b>am bold</b> becomes am bold. Note this filter is deprecated in PHP 8.1; use htmlspecialchars() instead.

The code below uses a custom function to send secure mail.

<?php
function sanitize_my_email($field) {
$field = filter_var($field, FILTER_SANITIZE_EMAIL);
if (filter_var($field, FILTER_VALIDATE_EMAIL)) {
return true;
} else {
return false;
}
}
$to_email = 'name@example.com';
$subject = 'Testing PHP Mail';
$message = 'This mail is sent using the PHP mail function';
$headers = 'From: noreply@example.com';
// check if the email address is invalid
$secure_check = sanitize_my_email($to_email);
if ($secure_check == false) {
echo "Invalid input";
} else { // send email
mail($to_email, $subject, $message, $headers);
echo "This email is sent using PHP Mail";
}
?>

Salida:

Seguro Mail

Los correos electrónicos pueden ser interceptados durante la transmisión por destinatarios no deseados.

This can expose the contents of the email to unintended recipients.

El correo seguro resuelve este problema mediante transmitting emails over an encrypted connection using SSL or TLS, for example SMTP over SSL on port 465 or STARTTLS on port 587.

Encryption scrambles the message before sending it, so only the intended recipient’s mail server can read it.

PHPMailer: A Better Alternative to mail()

For real applications, most developers use the PHPMailer library instead of the raw mail() function. PHPMailer authenticates with an external SMTP server, which greatly improves deliverability, and it makes attachments and HTML email simple.

Install it with Composer, then send mail through an authenticated, encrypted SMTP connection as shown below.

<?php
use PHPMailer\PHPMailer\PHPMailer;
require 'vendor/autoload.php';

$mail = new PHPMailer(true);
$mail->isSMTP();
$mail->Host = 'smtp.example.com';
$mail->SMTPAuth = true;
$mail->Username = 'user@example.com';
$mail->Password = 'secret';
$mail->SMTPSecure = 'tls';
$mail->Port = 587;

$mail->setFrom('noreply@example.com', 'My App');
$mail->addAddress('name@example.com');
$mail->Subject = 'Testing PHPMailer';
$mail->Body = 'This email is sent using PHPMailer over SMTP';
$mail->send();
?>

Compared with mail(), PHPMailer gives you SMTP authentication, built-in encryption, attachment support, and clearer error handling, which is why it is the recommended choice for production email.

Preguntas Frecuentes