peer certificate did not match "smtp.office354.com" using phpmailer - php

Question

Good Day,
I was having an error on my phpmailer smtp configuration to smtp.office365.com
here my script
require __DIR__ .'/vendor/phpmailer/phpmailer/src/Exception.php';
require __DIR__ .'/vendor/phpmailer/phpmailer/src/PHPMailer.php';
require __DIR__ .'/vendor/phpmailer/phpmailer/src/SMTP.php';
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;
use PHPMailer\PHPMailer\SMTP;
$mail = new PHPMailer(true); // Passing `true` enables exceptions
try {
//Server settings
$mail->SMTPDebug = 4; // Enable verbose debug output
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host = gethostbyname('smtp.office365.com'); // Specify main and backup SMTP servers
$mail->SMTPSecure = 'tls'; // Enable TLS encryption, `ssl` also accepted
$mail->SMTPAuth = true; // Enable SMTP authentication
$mail->Username = 'office365 username'; // SMTP username
$mail->Password = 'office365 password'; // SMTP password
$mail->SMTPOptions = array (
'ssl' => array(
// 'verify_peer' => false,
// 'verify_peer_name' => false,
// 'allow_self_signed' => true
));
$mail->Port = 587; // TCP port to connect to
//Recipients
$mail->From = $mail->Username;
$mail->addAddress('recipient#gmail.com'); // Name is optional
//Attachments
//Content
$mail->isHTML(true); // Set email format to HTML
$mail->Subject = 'Here is the subject';
$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';
$mail->send();
echo 'Message has been sent';
} catch (Exception $e) {
echo 'Message could not be sent.';
echo 'Mailer Error: ' . $mail->ErrorInfo;
}
I got this error
stream_socket_enable_crypto(): Peer certificate CN=`servername.com' did not match expected CN=`smtp.office365.com'
if I uncomment
$mail->SMTPOptions = array (
'ssl' => array(
// 'verify_peer' => false,
'peer_name' => 'smtp.office365.com',
// 'verify_peer_name' => false,
// 'allow_self_signed' => true
));
I still get authentication failure..
Im not really good with server configuration as someone is doing the server set up. but my site is on https.

Answer 1

Think about what this means. You’re asking to connect to a named host, but the name on the certificate does not match. That means that either the server is misconfigured (unlikely for office365), or you are being redirected to a different server that’s using a different name. This is extremely likely, as it’s very common in large hosting providers. All will be revealed if you set SMTPDebug = 2, as the troubleshooting guide the error message links to suggests.
That this has happened is a good thing - it’s one of the main reasons for using TLS - it not only encrypts your traffic in transit, but provided assurance that the server you connected to is the one you expected, i.e. it is doing its job properly.