PHPMailer Connects but not sending (Google XOAUTH2) - smtp

Question

Can anyone interpret the following output from PHPMailer and diagnose the problem? I have successfully tested my code in isolation but after incorporating into an application it fails
2021-08-19 14:25:31 3 Connection: opening to ssl://smtp.gmail.com:465, timeout=300, options=array()
2021-08-19 14:25:31 3 Connection: opened
2021-08-19 14:25:31 2 SERVER -> CLIENT: 220 smtp.gmail.com ESMTP q184sm1663611qkd.35 - gsmtp
2021-08-19 14:25:31 1 CLIENT -> SERVER: EHLO localhost
2021-08-19 14:25:31 2 SERVER -> CLIENT: 250-smtp.gmail.com at your service, [2607:fea8:e2c0:5dd:6c0a:3ddc:897:57d9]
250-SIZE 35882577
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
2021-08-19 14:25:31
2021-08-19 14:25:31 1 CLIENT -> SERVER: QUIT
2021-08-19 14:25:32 2 SERVER -> CLIENT: 221 2.0.0 closing connection q184sm1663611qkd.35 - gsmtp
2021-08-19 14:25:32 3 Connection: closed
The code is based on the XOAUTH2 example in the PHPMailer documentation. The essential function is here:
//Import PHPMailer classes into the global namespace
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
use PHPMailer\PHPMailer\OAuth;
//Alias the League Google OAuth2 provider class
use League\OAuth2\Client\Provider\Google;
class MainController extends Controller
{
function sendPHPMail($to, $name, $reply, $subject, $body, $attach, $type) {
// This function sends an HTML email via Google's SMTP server using XOAUTH2
//Create a new PHPMailer instance
$mail = new PHPMailer();
//Tell PHPMailer to use SMTP
$mail->isSMTP();
//Enable SMTP debugging
//SMTP::DEBUG_OFF = off (for production use)
//SMTP::DEBUG_CLIENT = client messages
//SMTP::DEBUG_SERVER = client and server messages
$mail->SMTPDebug = SMTP::DEBUG_CONNECTION;
$mail->Debugoutput = function($str, $level) {
file_put_contents('smtp.txt', gmdate('Y-m-d H:i:s'). "\t$level\t$str\n", FILE_APPEND | LOCK_EX);
};
//Set the hostname of the mail server
$mail->Host = $this->f3->get('mailHost');
//Set the SMTP port number:
// - 465 for SMTP with implicit TLS, a.k.a. RFC8314 SMTPS or
// - 587 for SMTP+STARTTLS
$mail->Port = 465;
//Set the encryption mechanism to use:
// - SMTPS (implicit TLS on port 465) or
// - STARTTLS (explicit TLS on port 587)
$mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
//Whether to use SMTP authentication
$mail->SMTPAuth = true;
//Set AuthType to use XOAUTH2
$mail->AuthType = 'XOAUTH2';
//Fill in authentication details here
//Either the gmail account owner, or the user that gave consent
$emailUser = $this->f3->get('mailUser');
$clientId = $this->f3->get('oauthClientID');
$clientSecret = $this->f3->get('oauthClientSecret');
// Refresh Token obtained by configuring and running get_oauth_token.php
// after setting up an app in Google Developer Console.
$refreshToken = $this->f3->get('oauthRefreshToken');
//Create a new OAuth2 provider instance
$provider = new Google(
[
'clientId' => $clientId,
'clientSecret' => $clientSecret,
]
);
//Pass the OAuth provider instance to PHPMailer
$mail->setOAuth(
new OAuth(
[
'provider' => $provider,
'clientId' => $clientId,
'clientSecret' => $clientSecret,
'refreshToken' => $refreshToken,
'userName' => $emailUser,
]
)
);
//Set who the message is to be sent from
//For gmail, this generally needs to be the same as the user you logged in as
$mail->setFrom($emailUser, "Mississippi Valley Textile Museum");
$mail->addReplyTo($reply);
//Set who the message is to be sent to
$mail->addAddress($to, $name);
//Set the subject line
$mail->Subject = $subject;
//Set HTML message body, convert referenced images to embedded
//Specify a basic plain-text alternative body
$mail->CharSet = PHPMailer::CHARSET_UTF8;
$mail->msgHTML($body);
//Replace the plain text body with one created manually
$mail->AltBody = 'This email is HTML; enable HTML mail if you cannot see it.';
//Add attachment if specified
if ($attach) {
$mail->addStringAttachment($attach, "MVTM{$type}.pdf"); }
//send the message, catch and log errors
try {
return $mail->send();
} catch (phpmailerException $e) {
file_put_contents('smtp.txt', gmdate('Y-m-d H:i:s'). "\n$e->errorMessage\n", FILE_APPEND | LOCK_EX);
//Pretty error messages from PHPMailer
return false;
} catch (Exception $e) {
file_put_contents('smtp.txt', gmdate('Y-m-d H:i:s'). "\n$e->errorMessage\n", FILE_APPEND | LOCK_EX);
// error messages from anything else
return false;
}
}
It appears to get by the initial connection but not the actual transmission to the smtp server

Answer 1

Solved. OK, there is nothing wrong with my code as shown here. The problem was in my app config file which hold the ClientSecret and RefreshToken. I had used single rather than double quotes which caused an escape to be misinterpretted. 3 days wasted but lesson learned.