Send email with PHPMailer and SMTP, default and Plesk

0-send-email-plesk.php

<?php
    
date_default_timezone_set('Europe/Madrid');
require_once 'PHPMailer-5.2.16/PHPMailerAutoload.php';

$mail = new PHPMailer;
$mail->isSMTP();
$mail->SMTPDebug = 2; # 0 off, 1 client, 2 client y server
$mail->CharSet  = 'UTF-8';

$mail->Host = 'localhost';
$mail->Port = 25;
$mail->SMTPSecure = 'tls'; # SSL is deprecated
$mail->SMTPOptions = array (
    'ssl' => array(
        'verify_peer'  => true,
        'verify_depth' => 3,
        'allow_self_signed' => true,
        'peer_name' => 'Plesk',
    )
);

$mail->SMTPAuth = true;
$mail->Username = 'smtp username';
$mail->Password = 'smtp password';

$mail->setFrom('email@domain.tld', 'Name Surname');
$mail->addAddress('email@domain.tld', 'Name Surname');
$mail->Subject = 'Email subject';
$mail->msgHTML('Email content with <strong>html</strong>');

if (!$mail->send()) {
    echo "Mailer Error: " . $mail->ErrorInfo;
} else {
    echo "Message sent!";
}

?>

1-send-email-default.php

<?php

# Include and load PHPMailer:
require_once 'libs/utils/PHPMailer-5.2.16/PHPMailerAutoload.php';
$mail = new PHPMailer();

# Config the SMTP
$mail->CharSet  = 'UTF-8';
$mail->IsSMTP();
$mail->Host     = '';
$mail->SMTPAuth = true;
$mail->Username = '';
$mail->Password = '';

# Set the mail
$mail->From     = '';
$mail->FromName = '';
$mail->AddAddress('email@domain.tld', 'Name Surname');
$mail->Subject = '';
$mail->Body    = '';

# Send
$mail->send();

?>