Sending mail with the Mail API

This guide describes how to use the Mail API to send mail.

Before you begin

Register your sender emails as authorized senders. For more information, see who can send email.

Sending mail

In PHP 7/8, the App Engine Mail function is no longer overloaded by default, and must be explicitly enabled. This new behavior lets you repurpose the Mail function to better suit your needs. This change also allows you to have visibility into which implementation is currently being used for all Mail function calls.

If you prefer using the native PHP mail() function to send mail using the App Engine Mail API, you can enable it in your php.ini file as follows:

extension = mailparse.so
sendmail_path = "php ./vendor/google/appengine-php-sdk/src/Runtime/SendMail.php -t -i"

Alternatively, you can make direct calls to the Mail API:


// Notice that $image_content_id is the optional Content-ID header value of the
// attachment. Must be enclosed by angle brackets (<>)
$image_content_id = '<image-content-id>';

// Pull in the raw file data of the image file to attach it to the message.
$image_data = file_get_contents('image.jpg');

try {
    $message = new Message();
    $message->setSender('from@example.com');
    $message->addTo('to@example.com');
    $message->setSubject('Example email');
    $message->setTextBody('Hello, world!');
    $message->addAttachment('image.jpg', $image_data, $image_content_id);
    $message->send();
    echo 'Mail Sent';
} catch (InvalidArgumentException $e) {
    echo 'There was an error';

Learn more about the migration considerations for the Mail API in the Accessing legacy bundled services for PHP guide.