fix: stop forwarding PhpMailer SMTP handshake to the logger

Sentry issue PHP-SYMFONY-2B accumulated 1034 events, each containing
the full PhpMailer SMTP debug dump: base64-encoded auth password,
recipient addresses and the message body. This happened because when
SMTP_DEBUG_LEVEL > 0, PhpMailer's Debugoutput callback was wired into
the Symfony logger, which then forwarded everything to Sentry at notice
level.

Fix: remove the Debugoutput -> logger wiring and the in-memory sendLog
buffer entirely. SMTPDebug still works for local debugging — PhpMailer
prints to stdout / error_log by default. Replace it with a single
info-level "Email sent" log carrying only recipient and subject.

Leaves the monolog Sentry handler threshold untouched.

Author: sveneld

src/Mail/PHPMailerMailSender.php

@@ -9,8 +9,6 @@
 
 class PHPMailerMailSender implements MailSenderInterface
 {
-    private array $sendLog = [];
-
     public function __construct(
         private readonly string $fromEmail,
         private readonly string $fromName,
@@ -26,10 +24,7 @@ public function sendMail($recipient, $subject, $message)
         $this->mailer->clearAllRecipients();
 
         $this->mailer->isSMTP(); // Set mailer to use SMTP
-        $this->mailer->SMTPDebug  = $this->debugLevel;
-        if ($this->debugLevel > 0 && $this->logger) {
-            $this->mailer->Debugoutput = $this->debugOutput(...);
-        }
+        $this->mailer->SMTPDebug = $this->debugLevel;
 
         $this->mailer->Host = $this->emailConfig["smtp_host"]; // Specify main and backup SMTP servers
         $this->mailer->Port = $this->emailConfig["smtp_port"]; // TCP port to connect to
@@ -44,23 +39,11 @@ public function sendMail($recipient, $subject, $message)
         $this->mailer->Subject = $subject;
         $this->mailer->Body = $message;
 
-        $this->sendLog = [];
         $this->mailer->send();
-        if ($this->debugLevel > 0 && $this->logger && $this->sendLog !== []) {
-            $this->saveSendLog();
-        }
-    }
-
-    /**
-     * @internal
-     */
-    public function debugOutput($str, $level): void
-    {
-        $this->sendLog[] = sprintf('[%s] %s', $level, $str);
-    }
 
-    private function saveSendLog(): void
-    {
-        $this->logger->notice('PhpMailer Debug', ['sendLog' => $this->sendLog]);
+        $this->logger?->info('Email sent', [
+            'recipient' => $recipient,
+            'subject' => $subject,
+        ]);
     }
 }