8 Best Free Transactional Email APIs for PHP (2026), Tested

$resend = Resend::client($_ENV['RESEND_API_KEY']);
$resend->emails->send([
    'from' => 'you@yourdomain.com',
    'to' => ['user@example.com'],
    'subject' => 'Hello',
    'html' => '<p>It works.</p>',
]);

$client = new Aws\SesV2\SesV2Client(['region' => 'us-east-1']);
$client->sendEmail([
    'FromEmailAddress' => 'you@yourdomain.com',
    'Destination' => ['ToAddresses' => ['user@example.com']],
    'Content' => ['Simple' => [
        'Subject' => ['Data' => 'Hello'],
        'Body' => ['Text' => ['Data' => 'It works.']],
    ]],
]);

$mail = new PHPMailer\PHPMailer\PHPMailer(true);
$mail->isSMTP();
$mail->Host = 'mail.smtp2go.com';
$mail->Port = 587;
$mail->SMTPAuth = true;
$mail->Username = $_ENV['SMTP_USER'];
$mail->Password = $_ENV['SMTP_PASS'];
$mail->setFrom('you@yourdomain.com');
$mail->addAddress('user@example.com');
$mail->Subject = 'Hello';
$mail->Body = 'It works.';
$mail->send();